The excision of 8-oxoguanine (oxoG) by the human 8-oxoguanine DNA glycosylase 1 (hOGG1) base-excision repair enzyme was studied by using the QM/MM (M06-2X/6-31G(d,p):OPLS2005) calculation method and nuclear magnetic resonance (NMR) spectroscopy. The calculated glycosylase reaction included excision of the oxoG base, formation of Lys249-ribose enzyme-substrate covalent adduct and formation of a Schiff base. The formation of a Schiff base with ΔG# = 17.7 kcal/mol was the rate-limiting step of the reaction. The excision of the oxoG base with ΔG# = 16.1 kcal/mol proceeded via substitution of the C1΄-N9 N-glycosidic bond with an H-N9 bond where the negative charge on the oxoG base and the positive charge on the ribose were compensated in a concerted manner by NH3+(Lys249) and CO2-(Asp268), respectively. The effect of Asp268 on the oxoG excision was demonstrated with 1H NMR for WT hOGG1 and the hOGG1(D268N) mutant: the excision of oxoG was notably suppressed when Asp268 was mutated to Asn. The loss of the base-excision function was rationalized with QM/MM calculations and Asp268 was confirmed as the electrostatic stabilizer of ribose oxocarbenium through the initial base-excision step of DNA repair. The NMR experiments and QM/MM calculations consistently illustrated the base-excision reaction operated by hOGG1.

• MeSH
• biokatalýza MeSH
• DNA-glykosylasy chemie   metabolismus   MeSH
• guanin analogy a deriváty   metabolismus   MeSH
• kyselina aspartová metabolismus   MeSH
• lidé MeSH
• lysin metabolismus   MeSH
• molekulární modely MeSH
• mutantní proteiny chemie   metabolismus   MeSH
• oprava DNA * MeSH
• protonová magnetická rezonanční spektroskopie MeSH
• termodynamika MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

This article suggests a new mechanistic scheme of the catalytic 8-oxoguanine excision with the hOGG1 base excision repair protein. The energy-efficient and substratespecific scheme employs enforced pyramidalization of the glycosidic nitrogen in the nucleobase within the hOGG1 catalytic pocket.

• Klíčová slova
• human 8-oxoguanine glycosylase1 protein,
• MeSH
• chemické jevy MeSH
• deoxyguanosin chemie   MeSH
• DNA-glykosylasy * chemie   MeSH
• enzymy opravy DNA * chemie   MeSH
• lidé MeSH
• molekulární modely MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH

Many aspects of protein function regulation require specific protein-protein interactions to carry out the exact biochemical and cellular functions. The highly conserved members of the 14-3-3 protein family mediate such interactions and through binding to hundreds of other proteins provide multitude of regulatory functions, thus playing key roles in many cellular processes. The 14-3-3 protein binding can affect the function of the target protein in many ways including the modulation of its enzyme activity, its subcellular localization, its structure and stability, or its molecular interactions. In this minireview, we focus on mechanisms of the 14-3-3 protein-dependent regulation of three important 14-3-3 binding partners: yeast neutral trehalase Nth1, regulator of G-protein signaling 3 (RGS3), and phosducin.

• MeSH
• DNA-glykosylasy chemie   ultrastruktura   MeSH
• DNA-lyasa (apurinová nebo apyrimidinová) chemie   ultrastruktura   MeSH
• fosfoproteiny chemie   ultrastruktura   MeSH
• konformace proteinů MeSH
• lidé MeSH
• molekulární sekvence - údaje MeSH
• multienzymové komplexy chemie   ultrastruktura   MeSH
• oční proteiny chemie   ultrastruktura   MeSH
• proteiny 14-3-3 chemie   ultrastruktura   MeSH
• proteiny RGS chemie   ultrastruktura   MeSH
• proteiny vázající GTP - regulátory chemie   ultrastruktura   MeSH
• Schizosaccharomyces pombe - proteiny chemie   ultrastruktura   MeSH
• sekvence aminokyselin MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• vztahy mezi strukturou a aktivitou MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Hyper-IgM syndrom je zajímavou skupinou onemocnění, jejichž podkladem je porucha změny izotypu produkovaných protilátek. Studium poruch u jednotlivých typů hyper-IgM syndromu umožnilo velký rozvoj poznání principů class-switch rekombinace a somatické hypermutace. Přes obrovský pokrok v objasňování molekulárně genetické podstaty poruch zůstávají stále "bílá místa". Autoři prezentují souhrn posledních poznatků a doplňují kazuistiku jednoho pacienta s X-vázaným hyper-IgM syndromem v péči jejich pracoviště.

Hyper-IgM syndrome is a very interesting group of diseases, which have in common a class-switch defect of produced antibodies. The study of specific defects underlying different types of hyper-IgM syndrome allowed development of knowledge about class-switch and somatic hypermutation principles. Despite the tremendous advance in enlightening the molecular genetic basis of the defects, white areas still remain. The authors present an overview of latest knowledge together with a case-study of the single patient with X-linked hyper-IgM syndrome in the care of their department.

• MeSH
• agamaglobulinemie diagnóza   etiologie   farmakoterapie   MeSH
• antigeny CD40 fyziologie   MeSH
• bodová mutace MeSH
• cytidindeaminasa antagonisté a inhibitory   fyziologie   genetika   MeSH
• DNA-glykosylasy fyziologie   genetika   chemie   MeSH
• imunoglobulin M fyziologie   genetika   krev   MeSH
• lidé MeSH
• přehledová literatura jako téma MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• kazuistiky MeSH