Enzymatic activities and DNA substrate specificity of Mycobacterium tuberculosis DNA helicase XPB.

XPB, also known as ERCC3 and RAD25, is a 3' → 5' DNA repair helicase belonging to the superfamily 2 of helicases. XPB is an essential core subunit of the eukaryotic basal transcription factor complex TFIIH. It has two well-established functions: in the context of damaged DNA, XPB facilitat...

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Autores principales:	Seetha V Balasingham, Ephrem Debebe Zegeye, Håvard Homberset, Marie L Rossi, Jon K Laerdahl, Vilhelm A Bohr, Tone Tønjum
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2012
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/4854c8dabf3346b0a41cc1e7eba6d88b
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spelling	oai:doaj.org-article:4854c8dabf3346b0a41cc1e7eba6d88b2021-11-18T07:18:32ZEnzymatic activities and DNA substrate specificity of Mycobacterium tuberculosis DNA helicase XPB.1932-620310.1371/journal.pone.0036960https://doaj.org/article/4854c8dabf3346b0a41cc1e7eba6d88b2012-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22615856/?tool=EBIhttps://doaj.org/toc/1932-6203XPB, also known as ERCC3 and RAD25, is a 3' → 5' DNA repair helicase belonging to the superfamily 2 of helicases. XPB is an essential core subunit of the eukaryotic basal transcription factor complex TFIIH. It has two well-established functions: in the context of damaged DNA, XPB facilitates nucleotide excision repair by unwinding double stranded DNA (dsDNA) surrounding a DNA lesion; while in the context of actively transcribing genes, XPB facilitates initiation of RNA polymerase II transcription at gene promoters. Human and other eukaryotic XPB homologs are relatively well characterized compared to conserved homologs found in mycobacteria and archaea. However, more insight into the function of bacterial helicases is central to understanding the mechanism of DNA metabolism and pathogenesis in general. Here, we characterized Mycobacterium tuberculosis XPB (Mtb XPB), a 3'→5' DNA helicase with DNA-dependent ATPase activity. Mtb XPB efficiently catalyzed DNA unwinding in the presence of significant excess of enzyme. The unwinding activity was fueled by ATP or dATP in the presence of Mg(2+)/Mn(2+). Consistent with the 3'→5' polarity of this bacterial XPB helicase, the enzyme required a DNA substrate with a 3' overhang of 15 nucleotides or more. Although Mtb XPB efficiently unwound DNA model substrates with a 3' DNA tail, it was not active on substrates containing a 3' RNA tail. We also found that Mtb XPB efficiently catalyzed ATP-independent annealing of complementary DNA strands. These observations significantly enhance our understanding of the biological roles of Mtb XPB.Seetha V BalasinghamEphrem Debebe ZegeyeHåvard HombersetMarie L RossiJon K LaerdahlVilhelm A BohrTone TønjumPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 7, Iss 5, p e36960 (2012)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Seetha V Balasingham Ephrem Debebe Zegeye Håvard Homberset Marie L Rossi Jon K Laerdahl Vilhelm A Bohr Tone Tønjum Enzymatic activities and DNA substrate specificity of Mycobacterium tuberculosis DNA helicase XPB.
description	XPB, also known as ERCC3 and RAD25, is a 3' → 5' DNA repair helicase belonging to the superfamily 2 of helicases. XPB is an essential core subunit of the eukaryotic basal transcription factor complex TFIIH. It has two well-established functions: in the context of damaged DNA, XPB facilitates nucleotide excision repair by unwinding double stranded DNA (dsDNA) surrounding a DNA lesion; while in the context of actively transcribing genes, XPB facilitates initiation of RNA polymerase II transcription at gene promoters. Human and other eukaryotic XPB homologs are relatively well characterized compared to conserved homologs found in mycobacteria and archaea. However, more insight into the function of bacterial helicases is central to understanding the mechanism of DNA metabolism and pathogenesis in general. Here, we characterized Mycobacterium tuberculosis XPB (Mtb XPB), a 3'→5' DNA helicase with DNA-dependent ATPase activity. Mtb XPB efficiently catalyzed DNA unwinding in the presence of significant excess of enzyme. The unwinding activity was fueled by ATP or dATP in the presence of Mg(2+)/Mn(2+). Consistent with the 3'→5' polarity of this bacterial XPB helicase, the enzyme required a DNA substrate with a 3' overhang of 15 nucleotides or more. Although Mtb XPB efficiently unwound DNA model substrates with a 3' DNA tail, it was not active on substrates containing a 3' RNA tail. We also found that Mtb XPB efficiently catalyzed ATP-independent annealing of complementary DNA strands. These observations significantly enhance our understanding of the biological roles of Mtb XPB.
format	article
author	Seetha V Balasingham Ephrem Debebe Zegeye Håvard Homberset Marie L Rossi Jon K Laerdahl Vilhelm A Bohr Tone Tønjum
author_facet	Seetha V Balasingham Ephrem Debebe Zegeye Håvard Homberset Marie L Rossi Jon K Laerdahl Vilhelm A Bohr Tone Tønjum
author_sort	Seetha V Balasingham
title	Enzymatic activities and DNA substrate specificity of Mycobacterium tuberculosis DNA helicase XPB.
title_short	Enzymatic activities and DNA substrate specificity of Mycobacterium tuberculosis DNA helicase XPB.
title_full	Enzymatic activities and DNA substrate specificity of Mycobacterium tuberculosis DNA helicase XPB.
title_fullStr	Enzymatic activities and DNA substrate specificity of Mycobacterium tuberculosis DNA helicase XPB.
title_full_unstemmed	Enzymatic activities and DNA substrate specificity of Mycobacterium tuberculosis DNA helicase XPB.
title_sort	enzymatic activities and dna substrate specificity of mycobacterium tuberculosis dna helicase xpb.
publisher	Public Library of Science (PLoS)
publishDate	2012
url	https://doaj.org/article/4854c8dabf3346b0a41cc1e7eba6d88b
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Enzymatic activities and DNA substrate specificity of Mycobacterium tuberculosis DNA helicase XPB.

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