Genetic and biochemical characterization of protein complexes that are essential for bacterial chromosome segregation and maintenance

蛋白质-蛋白质相互作用（分子“握手”）对于所有生物体的运作和功能至关重要。这些相互作用界面通常由来自每个蛋白质伴侣的关键氨基酸残基的子集形成。界面残基通常在直系同源物之间变化，表明一定程度的可变性或简并性。但目前还不清楚界面的可塑性如何，以及界面上关键氨基酸残基的组合如何支持强大而特异的蛋白质-蛋白质相互作用。这个DTP博士项目的目的是全面地分析祖先蛋白ParB周围的序列空间，这对细菌染色体分离至关重要。学生将：（i）通过饱和诱变和深度测序，研究所有可能的突变和对ParB-ParB相互作用至关重要的氨基酸子集突变组合对功能的影响。(ii)通过体外和体内技术的组合验证所鉴定的ParB变体的功能性。(ii)将突变序列空间投影到ParB的三维结构上，以充分展示序列-结构-功能关系。我们使用新月柄杆菌染色体分配蛋白B（ParB）作为本项目的理想模型系统。

Protein-protein interactions (molecular "handshakes") are crucial for the operation and function of all living organisms. These interaction interface are often formed by a subset of key amino acid residues from each protein partner. Interfacial residues often vary between orthologs, indicating some degree of mutability or degeneracy. But it is unclear how plastic the interface is and how the combination of key amino acid residues at the interface supports a robust and specific protein-protein interaction. This DTP PhD project aims to comprehensively characterise the sequence space around an ancestral protein ParB that is crucial for bacterial chromosome segregation. The student will:(i) characterise the effect on functions of all possible mutations and combination of mutations at a subset of amino acids that are crucial for ParB-ParB interaction by saturated mutagenesis and deep sequencing.(ii) validate the functionality of the identified ParB variants by a combination of in vitro and in vivo techniques.(ii) project the mutational sequence space on to the three-dimensional structure of ParB to fully characterise the sequence-structure-function relationship. We use the Caulobacter crescentus chromosome partitioning protein B (ParB) as an ideal model system for this project.