TY - JOUR
T1 - DNA clasping by mycobacterial HU
T2 - The c-terminal region of HupB mediates increased specificity of DNA binding
AU - Kumar, Sandeep
AU - Sardesai, Abhijit A.
AU - Basu, Debashree
AU - Muniyappa, Kalappagowda
AU - Hasnain, Seyed E.
PY - 2010
Y1 - 2010
N2 - Background: HU a small, basic, histone like protein is a major component of the bacterial nucleoid. E. coli has two subunits of HU coded by hupA and hupB genes whereas Mycobacterium tuberculosis (Mtb) has only one subunit of HU coded by ORF Rv2986c (hupB gene). One noticeable feature regarding Mtb HupB, based on sequence alignment of HU orthologs from different bacteria, was that HupBMtb bears at its C-terminal end, a highly basic extension and this prompted an examination of its role in Mtb HupB function.&Methodology/Principal Findings: With this objective two clones of Mtb HupB were generated; one expressing full length HupB protein (HupBMtb) and another which expresses only the N terminal region (first 95 amino acid) of hupB (HupBMtbN). Gel retardation assays revealed that HupBMtbN is almost like E. coli HU (heat stable nucleoid protein) in terms of its DNA binding, with a binding constant (Kd) for linear dsDNA greater than 1000 nM, a value comparable to that obtained for the HUα α and HUα β forms. However CTR (C-terminal Region) of HupBMtb imparts greater specificity in DNA binding. HupBMtb protein binds more strongly to supercoiled plasmid DNA than to linear DNA, also this binding is very stable as it provides DNase I protection even up to 5 minutes. Similar results were obtained when the abilities of both proteins to mediate protection against DNA strand cleavage by hydroxyl radicals generated by the Fenton's reaction, were compared. It was also observed that both the proteins have DNA binding preference for A:T rich DNA which may occur at the regulatory regions of ORFs and the oriC region of Mtb.&Conclusions/Significance:These data thus point that HupBMtb may participate in chromosome organization in-vivo, it may also play a passive, possibly an architectural role. & copy; 2010 Kumar et al.
AB - Background: HU a small, basic, histone like protein is a major component of the bacterial nucleoid. E. coli has two subunits of HU coded by hupA and hupB genes whereas Mycobacterium tuberculosis (Mtb) has only one subunit of HU coded by ORF Rv2986c (hupB gene). One noticeable feature regarding Mtb HupB, based on sequence alignment of HU orthologs from different bacteria, was that HupBMtb bears at its C-terminal end, a highly basic extension and this prompted an examination of its role in Mtb HupB function.&Methodology/Principal Findings: With this objective two clones of Mtb HupB were generated; one expressing full length HupB protein (HupBMtb) and another which expresses only the N terminal region (first 95 amino acid) of hupB (HupBMtbN). Gel retardation assays revealed that HupBMtbN is almost like E. coli HU (heat stable nucleoid protein) in terms of its DNA binding, with a binding constant (Kd) for linear dsDNA greater than 1000 nM, a value comparable to that obtained for the HUα α and HUα β forms. However CTR (C-terminal Region) of HupBMtb imparts greater specificity in DNA binding. HupBMtb protein binds more strongly to supercoiled plasmid DNA than to linear DNA, also this binding is very stable as it provides DNase I protection even up to 5 minutes. Similar results were obtained when the abilities of both proteins to mediate protection against DNA strand cleavage by hydroxyl radicals generated by the Fenton's reaction, were compared. It was also observed that both the proteins have DNA binding preference for A:T rich DNA which may occur at the regulatory regions of ORFs and the oriC region of Mtb.&Conclusions/Significance:These data thus point that HupBMtb may participate in chromosome organization in-vivo, it may also play a passive, possibly an architectural role. & copy; 2010 Kumar et al.
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U2 - 10.1371/journal.pone.0012551
DO - 10.1371/journal.pone.0012551
M3 - Article
C2 - 20824060
AN - SCOPUS:77958585144
SN - 1932-6203
VL - 5
SP - 1
EP - 10
JO - PloS one
JF - PloS one
IS - 9
M1 - e12551
ER -