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One evolutionarily selected amino acid variation is sufficient to provide functional specificity in the cold shock protein paralogs of Staphylococcus aureus
Author(s) -
CatalanMoreno Arancha,
Caballero Carlos J.,
Irurzun Naiara,
Cuesta Sergio,
LópezSagaseta Jacinto,
ToledoArana Alejandro
Publication year - 2020
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14446
Subject(s) - biology , complementation , cold shock domain , phenotype , amino acid , genetics , staphylococcus aureus , functional divergence , genome , peptide sequence , gene , bacteria , rna , gene family
Bacterial genomes encode several families of protein paralogs. Discrimination between functional divergence and redundancy among paralogs is challenging due to their sequence conservation. Here, we investigated whether the amino acid differences present in the cold shock protein (CSP) paralogs of Staphylococcus aureus were responsible for functional specificity. Since deletion of cspA reduces the synthesis of staphyloxanthin (STX), we used it as an in vivo reporter of CSP functionality. Complementation of a Δ cspA strain with the different S. aureus CSP variants showed that only CspA could specifically restore STX production by controlling the activity of the stress‐associated sigma B factor ( σ B ). To determine the amino acid residues responsible for CspA specificity, we created several chimeric CSPs that interchanged the amino acid differences between CspA and CspC, which shared the highest identity. We demonstrated that CspA Pro58 was responsible for the specific control of σ B activity and its associated phenotypes. Interestingly, CspC gained the biological function of CspA when the E58P substitution was introduced. This study highlights how just one evolutionarily selected amino acid change may be sufficient to modify the specific functionality of CSP paralogs.