Genetic, biochemical and structural characterisation of YecA, a novel component of the bacterial Sec machinery

[摘要] The Sec pathway provides a mechanism for the translocation of proteins across or into the cytoplasmic membrane. In bacteria, SecA is a core component of the Sec machinery. YecA has a 20-amino acid sequence at its carboxy-terminus that has high sequence identity to the zinc-binding domain at the carboxy-terminus of SecA. This study provides evidence to show that YecA is a novel component of the Sec machinery of E. coli. The yecA gene is not essential for the viability of E. coli but the deletion of yecA interferes with Sec-dependent translocation and the combined deletion of the yecA and secB genes results in a severely cold-sensitive phenotype. The genetic investigations were supported by biochemical evidence that suggests that YecA improves the translocation-coupled ATPase activity of SecA. Structural investigations suggest that YecA is a monomer in solution. The α-helical domain that forms the main body of YecA is connected via a short linker with limited flexibility to an independent metal-binding domain that has two conformations. The purification of YecA suggested the presence of iron. Biophysical experiments were used to confirm the interaction of the YecA metal-binding domain with iron. This study provides evidence for an additional component of the translocation machinery.

[发布机构] University:University of Birmingham;Department:School of Biosciences

[关键词] Q Science;QR Microbiology