Hester Christina M, Lutkenhaus Joe
Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
Proc Natl Acad Sci U S A. 2007 Dec 18;104(51):20326-31. doi: 10.1073/pnas.0705196105. Epub 2007 Dec 11.
Soj is a member of the ParA family of ATPases involved in plasmid and chromosomal segregation. It binds nonspecifically and cooperatively to DNA although the function of this binding is unknown. Here, we show that mutation of conserved arginine residues that map to the surface of Bacillus subtilis Soj caused only minimal effects on nucleotide-dependent dimerization but had dramatic effects on DNA binding. Using a model plasmid partitioning system in Escherichia coli, we find that Soj DNA-binding mutants are deficient in plasmid segregation. The location of the arginines on the Soj structure explains why DNA binding depends on dimerization and was used to orient the Soj dimer on the DNA, revealing the axis of Soj polymerization. The arginine residues are conserved among other chromosomal homologues, including the ParAs from Caulobacter crescentus, Pseudomonas aeruginosa, Pseudomonas putida, Streptomyces coelicolor, and chromosome I of Vibrio cholerae indicating that DNA binding is a common feature of members of this family.
Soj是参与质粒和染色体分离的ATP酶ParA家族的成员。它能非特异性且协同地结合DNA，尽管这种结合的功能尚不清楚。在这里，我们表明，定位在枯草芽孢杆菌Soj表面的保守精氨酸残基的突变对核苷酸依赖性二聚化仅产生最小影响，但对DNA结合有显著影响。使用大肠杆菌中的模型质粒分配系统，我们发现Soj DNA结合突变体在质粒分离方面存在缺陷。精氨酸在Soj结构上的位置解释了为什么DNA结合依赖于二聚化，并被用于确定Soj二聚体在DNA上的方向，揭示了Soj聚合的轴。精氨酸残基在其他染色体同源物中是保守的，包括新月柄杆菌、铜绿假单胞菌、恶臭假单胞菌、天蓝色链霉菌的ParA以及霍乱弧菌染色体I，这表明DNA结合是该家族成员的共同特征。
