Abstract
The CRISPR-Cas cluster is found in many prokaryotic genomes including those of the Enterobacteriaceae family. Salmonella enterica serovar Typhi (S. Typhi) harbors a Type I-E CRISPR-Cas locus composed of cas3, cse1, cse2, cas7, cas5, cas6e, cas1, cas2, and a CRISPR1 array. In this work, it was determined that, in the absence of cas5 or cas2, the amount of the OmpC porin decreased substantially, whereas in individual cse2, cas6e, cas1, or cas3 null mutants, the OmpF porin was not observed in an electrophoretic profile of outer membrane proteins. Furthermore, the LysR-type transcriptional regulator LeuO was unable to positively regulate the expression of the quiescent OmpS2 porin, in individual S. Typhi cse2, cas5, cas6e, cas1, cas2, and cas3 mutants. Remarkably, the expression of the master porin regulator OmpR was dependent on the Cse2, Cas5, Cas6e, Cas1, Cas2, and Cas3 proteins. Therefore, the data suggest that the CRISPR-Cas system acts hierarchically on OmpR to control the synthesis of outer membrane proteins in S. Typhi.
Highlights
Microorganisms are constantly exposed to multiple viral infections and have developed many strategies to survive phage attack and invasion by foreign DNA
CRISPR-Cas Is Fundamental for the Synthesis of Major and Quiescent Outer Membrane Proteins in Salmonella Typhi
The results presented here showed that the Cse2, Cas5, Cas6e, Cas1, Cas2, and Cas3 proteins via the positive regulation of the two-component regulator OmpR, have a role in the major and quiescent outer membrane protein synthesis, since they control OmpC, OmpF, and OmpS2
Summary
Microorganisms are constantly exposed to multiple viral infections and have developed many strategies to survive phage attack and invasion by foreign DNA. One such strategy is the CRISPR-Cas bacterial immunological system (Barrangou et al, 2007). The hallmark of the CRISPR-Cas Type I system is the presence of the endonuclease Cas. The hallmark of the CRISPR-Cas Type I system is the presence of the endonuclease Cas3 This protein is involved in cleavage of exogenous target nucleic acids (Sinkunas et al, 2011; Westra et al, 2012). The Type III system uses the RAMP proteins and Cas nuclease to silence the invader (Samai et al, 2015; Elmore et al, 2016)
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