Histones - it ... Indima histones kwi DNA

Nucleic DNA zibandakanywa kwinucleus iiseli eukaryotic, Bulelani indawo apakishwe kwizakhiwo ezikhethekileyo. Xa cytology bagquma igama elikhethekileyo - histones. It is a peptide ezivakalisa iipropati ezisisiseko imichiza. Isakhiwo labo kunye nemisebenzi eyenziwa esiseleni, eza kuxutyushwa kweli nqaku.

IDNA ulungiselelwe nucleus

Ukuze "sonke" polynucleotide chain elide iDNA microspace yeseli nucleus ekulo yinqobo "coil" - iiproteni, histones. Kokuba vulu kabini-ndixakene ukuba inxeba deoxyribonucleic acid. Esi sakhiwo, ibekwe karyoplasm kuthiwa nucleosome. izifundo kwemichiza luveze ukuba protein histone zilungiswe iinguqulelo ezininzi: H1 histone / H5, H2A, H2B, H3, h4. I peptide lokuqala koluluhlu kuthiwa linker, ezinye iinkomo. Ezi proteni histone zenza nucleosome.

Iimpawu ngesakhiwo of peptides nucleosome

uhlalutyo lwekhemikhali elisekwe ubunyani umxholo ngokugqithisileyo kwi core histone molecule acid ezifana lysine kunye arginine. Eyokuqala ibalulekile kwaye enye inxalenye interchangeable yaye ukho kuzo phantse zonke peptides. iiproteni Histone angemi umrhumo kwemfuneko elihle iintsalela acid acid. Bona Nokwethisa iintlawulo engakhiyo lilonke PO ₄ ^3- anions, zifakiwe kwi-DNA. Enye inkalo ngesakhiwo ezi kwiiproteni amanga neqiniso ukuba phantse twatse xa eziphilayo ukubayinxalenye ubukumkani kwezityalo, izilwanyana kunye nezinye izinto.

Ekubeni histones - kwiiproteni na undoqo, bona ngenxa nesakhiwo sayo, ungakwazi ukuthatha inxaxheba kwiinkqubo zenzeka karyoplasm. Hi xikombiso, le nto kubalulekile noshicilelo inkqubo H1 peptide - protein histone nucleosomes lokugcina bayinxalenye chromatin ngendlela ngocwangco, core indawo. Kwakhona, xa kukho DNA umonakalo ngeso, ekuthiwa-iimolekyuli peptide lobeko engundoqo ababandakanyekayo nokulungiswa la malungu.

peptide core

Bona ukuchaza isakhiwo nucleosome, equka ntlobo ezine ezibizwa H2A, H2B kunye H3 kunye h4. Ezi nucleosomes ezibini zohlobo ngalunye molecule, isakhiwo eso kuthiwa octamer. Le molecule iiprothini engundoqo ideoxyribonucleic kunye nefomu phakathi kwabo hydrophobic, hydrogen kunye imixokelelwane covalent. Iiproteni, histones zisisiseko le nucleosome. ukuba nayo efan NC-imisila. La malungu luqulathe 15-30 iintsalela acid acid kwaye ukubandakanyeka iinkqubo epigenetic abalawula gene nkulumo. histones Core nucleosomes kwisabelo esisezantsi abe ubunzima ezincinane eziphilayo, kwimimandla yabo, ngokungafaniyo nemisele umsila izabelo eziqulethwe monomers hydrophobic protein valine, proline, Lezina methionine.

Uphando lwakutsha nje entsimini ngamachiza zikhokelele hypothesis lwe khowudi histone. Mu kuya kwa nshita ikhowudi yezofuzo yi jikelele zonke iintlobo zobomi lweselula Emhlabeni, ikhowudi histone iyaguquguquka. Eli gama lithetha uguqulo kancincane iinxenye nomsila peptides ngenxa acetylation reaction, kwesipirithi, phosphorylation. Zonke ezi nkqubo amachiza kwenzeka phambi multienzyme izakhiwo. Ngenxa yeenkqubo kwemichiza ezinjalo, i uguqulo kancincane histones engundoqo, kwaye ukulungiswa kwenzeka yokubonisa zofuzo ezilawula ngayo intranuclear ebandakanya DNA: ukulungiswa, ukhutshelo, ukuphindaphindeka. Yena phantsi yempembelelo chromatin ikhowudi histone utshintsho ivavanywa zilungiswe, okt ukutshintsha kwikhava yayo nucleosome (azivingce, okanye ngokuchasene noko, uyayikhulula).

linker protein

Histone H1 ikuye chromatin, liqhagamshelene inxalenye olungaphandle nucleosome kwaye igcina kwalo supercoil deoxyribonucleic acid. nenkanuko yalo kwenzeka kwindawo tetramer ezibandakanya iimolekyuli ezimbini peptide H3 kunye h4 iimolekyuli ezimbini. Abameli eklasini kunye iklasi kweentaka ezirhubuluzayo e iiseli ezibomvu endaweni histone H1 linker protein wafumana enye H5.

peptide H1 yenziwa HMJB-domain - isahlulo lwesakhiwo, kunye nama-80 acid iintsalela acid. Nguye ifana kakhulu ezintweni ezininzi, kuquka izityalo, izilwanyana kunye nabantu. Le domain abawuthobeli ukuguqulwa kwaye ngendeb '. Peptide N1 uye iintlobo ezimbini sisimo lwendawo: a globule liwa, yaye zenzeka - ngendlela ephakamileyo. Le yokugqibela kwenzeka xa unxibelelwano akaphumeleli C-terminal kummandla histone ukuya domains DNA-yokubopha. Le peptide linker libandakanyeka ngokubonakalayo ukukotshwa iinkcukacha sofuzo ukuya mRNA molecule, noziqulathe-kabini iinkqubo DNA, kwakunye kwi lokulungiswa ezonakeleyo ngeso layo. Le indima yebhayoloji yolo histones kwi DNA.

Njengeprotini ifomu octamer

Ngokungafaniyo peptide H1, nezinye iintlobo histones ekuthiwa lenkomo, esibonakala ductility elaneleyo ukwenza ifomu lobeko. Umzekelo, H2A lelona zokuguqulwa: H2AZH2AX MACROH2A. Baya kwahluka enye kwenye:

• C-terminal ukulandelana acid acid.
• Indawo kwigenome.

Umzekelo, histone lobeko H2ABbd amaqhina oqhagamshelwano kunye chromatin apho kwenzeka DNA tumbuluxiwa. MACROH2A peptide ukho zofuzo interphase. izifundo Cytological kufunyaniswe ukuba iifom lobeko histone h4 luchongiwe, kodwa unako ukwenza inani elikhulu iibhondi covalent kunye nezinye kwiiproteni lilungu nucleosomes octamer. Ngenxa yoko, izazinzulu zikholelwa ukuba histones - iqela eyodwa ziiproteni ifana yinxalenye chromatin zonke iintlobo cellular zobomi.

Indlela ukugcina ulwazi malunga histones kwigenome

Kungaphikiswa ukuba iinkomo, kunye uhlobo linker histone okubhalwe kule ezisebenzisanayo zemfuza ichazwe kwisigaba zokwenziwa of the lomjikelo wobomi yeseli. Umzekelo, ukuba imikhwa zofuzo yabantu iqela elibizwa HIST1 liphethe genes 35 ibekwe kwindawo esabuvaranda somatic isibini chromosome. Iqela HIST2 yenziwa zijini ezintandathu ujiko histones, yaye indawo chromosomal ye kwisibini sokuqala. Kwakhona uqulathe HIST3 kuwela, eliquka zofuzo ezintathu. Xa isibini elinesibini yenye gene ujiko a h4 histone. Okubangel 'umdla kukuba, izakhi engundoqo protein babe introns, kunye zofuzo histones lobeko, phezu koko, ibe kuzo kwaye saa kulo lonke ufuzo.

Ukushwankathela, sibonile ukuba histones - proteins libandakanyeka ekubekeni nemidzaluka iDNA ngumongo, kodwa kwiinkqubo yommiselo, ukulungiswa kunye nokubhalwa kuqhutywa ngayo.