Yamagata Atsushi, Kakuta Yoshimitsu, Masui Ryoji, Fukuyama Keiichi
Department of Biology, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
Proc Natl Acad Sci U S A. 2002 Apr 30;99(9):5908-12. doi: 10.1073/pnas.092547099. Epub 2002 Apr 23.
RecJ, a 5' to 3' exonuclease specific for single-stranded DNA, functions in DNA repair and recombination systems. We determined the crystal structure of RecJ bound to Mn(2+) ion essential for its activity. RecJ has a novel fold in which two domains are interconnected by a long helix, forming a central groove. Mn(2+) is located on the wall of the groove and is coordinated by conserved residues characteristic of a family of phosphoesterases that includes RecJ proteins. The groove is composed of residues conserved among RecJ proteins and is positively charged. These findings and the narrow width of the groove indicate that the groove binds single- instead of double-stranded DNA.
RecJ是一种对单链DNA具有特异性的5'至3'核酸外切酶，在DNA修复和重组系统中发挥作用。我们确定了与对其活性至关重要的锰离子（Mn²⁺）结合的RecJ晶体结构。RecJ具有一种新颖的折叠结构，其中两个结构域由一个长螺旋相互连接，形成一个中央凹槽。Mn²⁺位于凹槽壁上，并由包括RecJ蛋白在内的磷酸酯酶家族特有的保守残基配位。该凹槽由RecJ蛋白中保守的残基组成，且带正电荷。这些发现以及凹槽的狭窄宽度表明该凹槽结合的是单链而非双链DNA。
