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[Music]

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[Applause]

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good afternoon everyone my name is

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Fillie way in this talk I'm going to

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present our recent study modern a study

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on self-assembly of short peptides in

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memory and how they would mediate ion

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transport the transport of ionic cores

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memory is very important for biochemical

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functions however the insistence of

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permeation through the memory is not

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energetically favorable and an energy

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barrier can be kankakee culpable so you

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early you need some help you need either

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iron transporter or ion channels and it

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cannot only low the free energy barrier

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it can also provide selectivity and

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regulation however different designs are

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in the contemporary art channel which

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has very high sequency requirement and

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has very high ion selectivity we expect

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that EEE only our channel the lands and

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the secrecy requirement is rather

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minimum and the ANSI selectivity is

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rather weak so to understand the early

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on channel the formation of it we use a

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rather or model system the modern

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channel we try to use is called is

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formed by antimicrobial peptides it is

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rather short it has only 8 to 20 amino

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acids and it is and fulfilling peptides

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and loss of exam had found this type of

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peptides can polymerize membrane and

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have ions and some molecules and vesicle

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content leakage

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one of the well studied antimicrobial

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peptide formation of Valentino is this

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ala missing peptide it has a length of

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20 amino acid and it is longer enough to

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span the membrane and has well-defined

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conductance however we want studies on

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seeing even shorter so we are trying to

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understand he was a peptide is even is

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much shorter than al amazing channel can

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it immediate transpose remember so with

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the peptide we true to study is this

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called trikuti peptide it has only 10

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sequence e and most of it is hydrophobic

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or sto and it has few crises rescue on

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it and this pipe has is rather high for

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helical conformation in memory it can

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either increase memory state or can be

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in a surface bounded state and they are

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interconvertible and experiment has

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found that this peptide can immobilize

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membrane and at a certain type ID to the

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padishah and even iron transporter arc

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has been observed however the mechanism

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of our transport is very weak so people

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propose the various mechanisms such as

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deformation of memory due to the peptide

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maybe there are channel formation

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maybe that who are water defects so our

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studies many focused try to understand

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this we use modeling a method basically

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we use atomic molecular dynamic

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simulations and to a solution every see

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the process we also use a society there

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are simulation which can lower the free

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energy overall in the system so we can

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study a long time scale of the process

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so we first try to understand with even

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just one single peptide a monomers here

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how the effects the memory structure so

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we found that we with this trend are

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transmembrane orientation of this single

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peptide is already induced local

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memories in effects and introduce the

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water defects from both side and such

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deformation is shown to lower water on

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free energy crossing the membrane for

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one kcal per mole and the water

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transport through the memory is found

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highly favorable in the neighborhood of

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this peptide

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however to think about this whether such

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deformation can induce iron transporter

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the possibilities rather are low because

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for ion to transport easily in either

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much larger water pool so

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to continue to understand it what we do

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what we did is that we have more than

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one peptides on the surface memory as

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you see on the far right far left side

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that's our initial confusion when we

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study the study the simulation we have

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14 of the tributing peptides initially

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as a memory surface because we want

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studies and transport so we apply

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electric field across a membrane so with

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the simulation progressed we see that

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the peptides began some of them began to

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adopt it is transmembrane conformation

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and as he began to irrigate and various

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irrigation state has been found they can

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be time well actually there are two

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types of tangled it can be try more and

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the Tetra more and with even longer

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simulation we found a ependymal

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structure on the snapshot were taken

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from our simulation on the right sides

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in most the right side so this kind of a

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structure actually is well-defined if I

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check the cross section of this Panama

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structure as sure on the top it is

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actually behave as a better state model

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it has this cry seen which is higher

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slightly hydrophilic residues facing the

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lumen officer of the of the arguments

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structure and also there what for quince

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reserve polymer and we observed iron and

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conductance Tiffany's waterfall and

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however I have it were mentioned that on

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such original structure although a

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contact ions it rather present so not

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only it have formed and he was

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structured Ramos structure it can it can

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assembled back to its original disorder

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structure so it is than any chimera turn

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any caused aggregation so if we want how

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to understand little bit about how this

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organ was formed there was a mechanism

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for the formation of the ugly more so

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quantitatively there are two steps to

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for it formed on the right side on the

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left side you can see if I have two

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peptides

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in inserting in the memory and each of

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them can cause local or membrane

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deformation and to have to reduce the

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total free energy of this of the

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sophistic earth of the memory

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deformation all these two peptides is

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time to aggregate and such total free

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energy is depending on the surface

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tension is depend on the pending

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stiffness of witchly PDR you see it also

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depend on the membranes Martinez

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curvature of the LDP so the second step

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is that once the true pipe has get close

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enough they will adjust to each other

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and have a sequence II dependent

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Alchemist structure so in our case we

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have a guy see rest you will face in the

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looming officer pentamer or the elegance

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of limas structure and the soul which is

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so we found that actually there are more

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than just the only most structural have

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this arm channel like structure actually

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the lipid can also be I induced to have

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a free flop motion constantly so due to

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the water defects induced by this

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special peptide the head group of the

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deep heat can go through a free flow

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process coming from one side of

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remembering to the other side ideally

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this process is kind introduce a

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transient water power and through this

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transient world poor aren't a transport

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through the memory also so this is kind

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of similar as people have been long

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proposed as this hurdle hope for some

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activity of antimicrobial peptides so

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this kind of in confirm that is it is

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possible so exciti was what high people

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have been observed in the antimicrobial

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peptides that people do find some

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I don't handle like activity and people

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also through recent years people have

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been used as TM eg try to understand the

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structure of this poll however I

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recommend that because different than

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the contemporary handle that people can

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study the structures through x-ray or

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NMR because of dynamic nature of this

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short peptides so it's very extremely

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Challenger to capture the real structure

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of it why is interaction so in

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conclusion we have study the short

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peptides a sense of assembly in the

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membrane we follow it immediate an

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transpose through various ways and we

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found that the short peptides have

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formed Optimus different Oklahoma

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structures through the membrane mediated

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our formation or we found that translate

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what Paul can be formed through the

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pentamer structure and iron can be

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transverse research structure we also

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found that memory and structure can be

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disrupted by peptide induced repeat a

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flip-flop and also iron transfer can is

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observers to such process so what's the

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implication of how study so it shows

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that short and simple and fulfilling

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peptides is capable to polymerizing

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memory so it suggests that maybe select

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peptides or they can be a candidate for

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the precursors or for continuing

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contemporary ion channels so this is a

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some good indication for that that would

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be concluding my talk thank you

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Thank You China we have time for many

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okay so this down standard an acid is

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called amino ethyle

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periodic acid so it is from it has fungi

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nature so it is generate post the

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translational process for the standard

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amino acid so yeah kind of like that

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yeah so regarding whether we can

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substituted with other amino acid such

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as standard city it's a little bit hard

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to see because why is it positive answer

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is that it is possible to replace it

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with a hydrophobic the aldehyde to stand

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out hydrophobic peptides amino acid so

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because of me function of it is is

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hydrophobic property and the other side

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unique about this amino acid is that it

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is hydrophobic it is a helical

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conformation promoter so as you can see

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in this specific sequence II it has lots

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of for AIB residue it promotes a helical

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conformation of these peptides so when

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people be substituting with other for

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example hydrophobic residue this might

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take into account whether it can

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influence some summary the properties of

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okay Thank You 10 you our next speaker