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

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Cranford-Smith, Tamar (2018). Genetic, biochemical and structural characterisation of YecA, a novel component of the bacterial Sec machinery. University of Birmingham. Ph.D.

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Abstract

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.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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