Histones - ke ... Indima histones ku-DNA

Nucleic acid DNA kufakwe i-nucleus ye amaseli eukaryotic, compact sibonga ezipakishiwe izakhiwo ezikhethekile. Ngo Cytology abazigqokayo igama ekhethekile - histones. Kuyinto peptide ukuthi ubonisa eziyisisekelo chemical izakhiwo. Ukwakheka kwazo ngokwama kanye nemisebenzi eyenziwa kuseli, kuzoxoxwa ngakho kulesi sihloko.

DNA okuhlelwe nucleus

Ukuze "Cindezela" eside polynucleotide uchungechunge DNA microspace iseli nucleus ezikulo ziyiziqondiso eyinqaba "ikhoyili" - amaprotheni, histones. Basuke ntambo kabili balahleke is nilimaza deoxyribonucleic acid. Lesi sakhiwo, elise karyoplasm ibizwa ngokuthi nucleosome. izifundo kwamakhemikhali wembula ukuthi amaprotheni histone ihlelwe ukulungiswa eziningana: H1 histone / h5, H2A, H2B, H3, H4. I peptide wokuqala kulolu hlu ibizwa ngokuthi linker, eduze lamankomokazi. Lezi amaprotheni histone yakha nucleosome.

Izici isakhiwo peptides nucleosome

ukuhlaziywa Chemical esungulwe yokuthi okuqukethwe ngokweqile kule core histone molecule amino acid ezifana lysine futhi arginine. Eyokuqala kubalulekile kanye nezinye kancane nezilandiso futhi likhona cishe kuzo zonke peptides. Histone amaprotheni buthelela ngokweqile icala omuhle izinsalela acid acid. Bona iwukudambisa amacala omubi Imininingwane PO ₄ ^3- anions, kufakwe DNA. Esinye isici isakhiwo yalezi amaprotheni itholakala lokuthi ukuthi kucishe e eziphilayo okuqondene umbuso phakathi kwezitshalo, izilwane kanye nesikhunta.

Njengoba histones - amaprotheni iyona core, zingabantu ngenxa isakhiwo yayo, iqhaza izinqubo ezenzeka e karyoplasm. Ngokwesibonelo, abaluleke kakhulu kuya umbhalo inqubo H1 peptide - amaprotheni histone esaziwa nucleosomes bayingxenye chromatin ngendlela ehlelekile, core ezihlangene. Futhi, uma ukulimala kwe-DNA loci, okuthiwa core peptide okufana molecule zinengxenye ukulungisa lezi izingxenye.

peptide core

Abakuchaza nokwakheka nucleosome, okuyinto uqukethe izinhlobo ezine zamathrekhi zishintshe ngokuthi H2A, H2B futhi H3 futhi H4. I nucleosomes ezimbili uhlobo-molecule ngamunye, isakhiwo esinjalo libizwa octamer. I-molecule core amaprotheni deoxyribonucleic futhi ifomu phakathi kwabo hydrophobic, i-hydrogen ne-covalent izibopho. Amaprotheni, histones ngaso umnyombo nucleosome. aqukethe akusenjalo NC-imisila. Lezi zingxenye ziqukethe 15-30 acid acid izinsalela futhi behileleke izinqubo epigenetic ezilawula isakhi sofuzo inkulumo. histones Core emaphakathi ingxenye nucleosomes babe encane isisindo yamangqamuzana, ezindaweni zabo, ngokungafani umsila izingxenye zesiqhingi equkethwe monomers hydrophobic amaprotheni valine, proline, Lezina methionine.

Ucwaningo lwamuva emkhakheni wokusebenza kwamakhemikhali ezintweni eziphilayo ziye zaholela umbono ikhodi histone. Ngokungafani isimiso sezakhi zofuzo kuyinto jikelele zonke izinhlobo zokuphila yeselula Emhlabeni, ikhodi histone kuyinto onhlobonhlobo. Le nkulumo isho ukuthi ukulungisa izingxenye umsila we peptides esukela acetylation ukuphendula, methylation, phosphorylation. Zonke lezi zinqubo kwamakhemikhali okwenzeka ngokuvumelana khona multienzyme izakhiwo. Ngenxa izinqubo ezinjalo kwamakhemikhali, lesi ukulungisa umnyombo histones, futhi ukulungiswa senzeka Inkulumo yezakhi zofuzo ezilawula ukusabela intranuclear ezihilela DNA: ukukhanda, umbhalo, ukufanisana. Ngokwakhe ngaphansi kwethonya chromatin ikhodi histone izinguquko asitholayo zilungiswe, okusho ekushintsheni kwikhava yawo ku nucleosome (eliqinisa noma, kunalokho, uthukulula).

linker amaprotheni

Histone H1 is e chromatin, ixhunywe ingxenye elingaphandle nucleosome futhi azigcina kwalo supercoil deoxyribonucleic acid. nenkanuko edlulele kwalo kwenzeka endaweni tetramer ehlanganisa molecule ezimbili peptide H3 futhi H4 molecule ezimbili. I abameleli besigaba futhi isigaba zezinyoni nezilwane ezihuquzelayo e amaseli abomvu egazi esikhundleni histone H1 linker amaprotheni atholakala kwenye h5.

peptide H1 yakhiwa HMJB-domain - ingxenye kwesakhiwo, abangaba ngu-80-amino acid izinsalela. He is cishe okufanayo eziningi eziphilayo, kuhlanganise izitshalo, izilwane kanye nabantu. Lesi sizinda lungekho ngaphansi ukuguqulwa futhi olandelanayo. Peptide uN1 has izinhlobo ezimbili ukucupha ngekwendzawo: a globule kubhidlika futhi zenzeka - ngefomu ephakeme. Lesi sakamuva kwenzeka uma ukukhulumisana ehluleka C-esibulalayo esifundeni histone kuya ezizindeni DNA-esibophezelayo. I peptide linker is bahileleke ukukopisha ulwazi kusuka isakhi sofuzo ku mRNA molecule izinqubo DNA self-kabili, kanye ukukhanda of ezilimele loci yayo. Lona indima begazi histones kuyi-DNA.

Njengoba amaprotheni yakha octamer

Ngokungafani peptide H1, nezinye izinhlobo histones ngokuthi inkomo, libhekene ductility anele ukwakha ifomu okufana. Ngokwesibonelo, H2A linenani eliphakeme zokuguqulwa: H2AZH2AX MACROH2A. Yehluka nomunye:

• C-esibulalayo acid acid ukulandelana.
• Indawo e ufuzo.

Ngokwesibonelo, histone okufana H2ABbd oxhumene nge chromatin lapho DNA umbhalo kwenzeka. MACROH2A peptide ungaphakathi interphase chromosome. izifundo Cytological kwatholakala ukuthi histone H4 okufana amafomu sezihlonziwe, kodwa ungakwazi akha inqwaba covalent izibopho namanye amaprotheni okuqondene nucleosomes octamer. Ngenxa yalokho, ososayensi bakholelwa ukuthi histones - eqenjini elithile amaprotheni ukuthi cishe ingxenye chromatin kuwo wonke amafomu yeselula zokuphila.

Indlela ukugcina ulwazi mayelana histones e ufuzo

Kungaba wagomela ukuthi izinkomo, kanye okufana linker histone okubhalwe ku amaqoqo isakhi sofuzo uzwakalise esigabeni zokwenziwa le umjikeleto wemphilo seli. Ngokwesibonelo, i-izici zobuntu lezinceku iqembu okuthiwa HIST1 liqukethe 35 izakhi zofuzo elise lesithupha ukuphathwa kwabathintwayo chromosome pair. HIST2 cluster yakhiwa izakhi zofuzo eziyisithupha ikhodi histones, kanye chromosomal indawo umbhangqwana wokuqala. Iphinde iqukethe HIST3 Locus, ehlanganisa izakhi zofuzo ezintathu. Esikhathini pair yeshumi nambili ingenye isakhi sofuzo ikhodi a H4 histone. Ngokuthakazelisayo, izakhi zofuzo eziyinhloko amaprotheni babe introns, futhi izakhi zofuzo okufana histones, kunalokho, aqukethe nabo chithi saka ufuzo.

Kufinyeta, sesibonile ukuthi histones - amaprotheni ehilelekile ebeka zingu-DNA-nucleus, kodwa futhi izinqubo wesi, ukulungisa kanye nokubhalwa zenzeke kuwo.