Roles of two large serine recombinases in mobilizing the methicillin‐resistance cassette SCCmec

Summary Methicillin‐resistant Staphylococcus aureus (MRSA) emerged via acquisition of a mobile element, staphylococcal cassette chromosome mec (SCCmec). Integration and excision of SCCmec is mediated by an unusual site‐specific recombination system. Most variants of SCCmec encode two recombinases, C...

Full description

Saved in:
Bibliographic Details
Published in:Molecular microbiology 2013-06, Vol.88 (6), p.1218-1229
Main Authors: Misiura, Agnieszka, Pigli, Ying Z., Boyle‐Vavra, Susan, Daum, Robert S., Boocock, Martin R., Rice, Phoebe A.
Format: Article
Language:English
Subjects:
Binding Sites
Deoxyribonucleic acid
DNA
DNA, Bacterial - metabolism
E coli
Enzymes
Escherichia coli
Escherichia coli - genetics
Evolution
Methicillin Resistance
Methicillin-Resistant Staphylococcus aureus - enzymology
Methicillin-Resistant Staphylococcus aureus - genetics
Microbiology
Multigene Family
Protein Binding
Recombinant Proteins - genetics
Recombinant Proteins - metabolism
Recombinases - genetics
Recombinases - metabolism
Recombination, Genetic
Staphylococcus aureus
Staphylococcus infections
Substrate Specificity
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Summary Methicillin‐resistant Staphylococcus aureus (MRSA) emerged via acquisition of a mobile element, staphylococcal cassette chromosome mec (SCCmec). Integration and excision of SCCmec is mediated by an unusual site‐specific recombination system. Most variants of SCCmec encode two recombinases, CcrA and CcrB, that belong to the large serine family. Since CcrA and CcrB are always found together, we sought to address their specific roles. We show here that CcrA and CcrB can carry out both excisive and integrative recombination in Escherichia coli in the absence of any host‐specific or SCCmec‐encoded cofactors. CcrA and CcrB are promiscuous in their substrate choice: they act on many non‐canonical pairs of recombination sites in addition to the canonical ones, which may explain tandem insertions into the SCCmec attachment site. Moreover, CcrB is always required, but CcrA is only required if one of the four half‐sites is present. Recombinational activity correlates with DNA binding: CcrA recognizes only that half‐site, which overlaps a conserved coding frame on the host chromosome. Therefore, we propose that CcrA serves as a specificity factor that emerged through modular evolution to enable recognition of a bacterial recombination site that is not an inverted repeat.
ISSN:0950-382X
1365-2958
DOI:10.1111/mmi.12253