2b5a
From Proteopedia
C.BclI, Control Element of the BclI Restriction-Modification System
Overview
Protection from DNA invasion is afforded by restriction-modification systems in many bacteria. The efficiency of protection depends crucially on the relative expression levels of restriction versus methytransferase genes. This regulation is provided by a controller protein, named C protein. Studies of the Bcll system in E. coli suggest that C.Bcll functions as a negative regulator for M.Bcll expression, implying that it plays a role in defense against foreign DNA during virus infection. C.Bcll binds (Kd = 14.3 nM) to a 2-fold symmetric C box DNA sequence that overlaps with the putative -35 promoter region upstream of the bcllM and bcllC genes. The C.Bcll fold comprises five alpha helices: two helices form a helix-turn-helix motif, and the remaining three helices form the extensive dimer interface. The C.Bcll-DNA model proposed suggests that DNA bending might play an important role in gene regulation, and that Glu27 and Asp31 in C.Bcll might function critically in the regulation.
About this Structure
Full crystallographic information is available from OCA.
Reference
Crystal structure of the restriction-modification system control element C.Bcll and mapping of its binding site., Sawaya MR, Zhu Z, Mersha F, Chan SH, Dabur R, Xu SY, Balendiran GK, Structure. 2005 Dec;13(12):1837-47. PMID:16338412 Page seeded by OCA on Sat May 3 19:52:28 2008
