Jayaram Makkuni
Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, TX 78712, USA.
Mol Microbiol. 2007 May;64(3):575-9. doi: 10.1111/j.1365-2958.2007.05700.x.
The ResT telomere resolvase is responsible for maintaining the hairpin telomeres that cap the linear chromosome and minichromosomes of Borrelia burgdorferi. This enzyme acts at the tandem telomere junctions present within circular dimers resulting from DNA replication. ResT mediates the transesterification steps of resolution using a constellation of active site residues similar to that found in tyrosine recombinases and type IB topoisomerases. By combining this reaction mechanism with a hairpin binding module in its N-terminal domain, ResT reduces a fused telomere dimer into two hairpin monomers. ResT displays a split DNA binding specificity, with the N- and C-terminal domains targeting distinct regions of the telomere. This bi-specificity in binding is likely to be important in protein delivery, substrate selection and regulation of enzyme activity.
ResT端粒解离酶负责维持伯氏疏螺旋体线性染色体和微型染色体末端的发夹状端粒。该酶作用于DNA复制产生的环状二聚体中存在的串联端粒连接点。ResT利用一组与酪氨酸重组酶和IB型拓扑异构酶中发现的活性位点残基相似的残基介导解离的转酯步骤。通过将这种反应机制与其N端结构域中的发夹结合模块相结合，ResT将融合的端粒二聚体还原为两个发夹单体。ResT表现出分裂的DNA结合特异性，其N端和C端结构域靶向端粒的不同区域。这种结合的双特异性可能在蛋白质传递、底物选择和酶活性调节中起重要作用。
