Elucidating the functional role of Mycobacterium smegmatis recX in stress response

Abstract

The RecX protein has attracted considerable interest because the recX mutants exhibit multiple phenotypes associated with RecA functions. To further our understanding of the functional relationship between recA and recX , the effect of different stress treatments on their expression profiles, cell yield and viability were investigated. A significant correlation was found between the expression of Mycobacterium smegmatis recA and recX genes at different stages of growth, and in response to different stress treatments albeit recX exhibiting lower transcript and protein abundance at the mid-log and stationary phases of the bacterial growth cycle. To ascertain their roles in vivo , a targeted deletion of the recX and recArecX was performed in M . smegmatis . The growth kinetics of these mutant strains and their sensitivity patterns to different stress treatments were assessed relative to the wild-type strain. The deletion of recA affected normal cell growth and survival, while recX deletion showed no significant effect. Interestingly, deletion of both recX and recA genes results in a phenotype that is intermediate between the phenotypes of the ΔrecA mutant and the wild-type strain. Collectively, these results reveal a previously unrecognized role for M . smegmatis recX and support the notion that it may regulate a subset of the yet unknown genes involved in normal cell growth and DNA-damage repair.

A hypoxia risk signature for the tumor immune microenvironment evaluation and prognosis prediction in acute myeloid leukemia

“…High degree of hypoxia can induce cell cycle arrest in a variety of cell types 45 , while CCNA2 is a key factor in cell cycle and could be up-regulated induced by hypoxia to promote cell proliferation 39 . Also, acute stress caused by hypoxia arrests DNA replication and triggers DNA damage 46 , while DNA replication supported by the complexes of CCNA2‐CDK could push forward the cell cycle in the S‐phase 47 . Besides, hypoxia has been reported to suppress DNA repair through homologous recombination 48 , while CCNA2 is located at sites of DNA double-strand breaks (DSB) and plays a role in homologous recombination 49 .…”

Elucidating the role of c-di-AMP in Mycobacterium smegmatis: phenotypic characterization and functional analysis

“…Next, we checked ΔdisA and Δpde mutants' survival patterns under different stresses and found that varying c-di-AMP concentration could play a definite role which is linked to underlying pathways yet to be discovered. The Δpde mutant was found to be very sensitive to UV irradiation compared to WT, possibly due to RecA enzyme's functional deficiency (46) and the ΔdisA strain has better survival under identical conditions. demonstrated.…”

The recombination regulator RecX negatively regulates heat-stable antifungal factor (HSAF) biosynthesis in Lysobacter enzymogenes

“…Several studies have demonstrated an alternative role for recX in the DNA repair of recombination performed by RecA (Pages et al 2003;Ragone et al 2008;Prasad et al 2019). The absence of RecX severely impaired the natural transformations in both plasmid and chromosomal DNA.…”

“…RecX abrogates RecA•ATP-hydrolysis, and strand exchange promoted by RecA and RecX might act as an anti-recombinase to inhibit inappropriate recombination repair during normal DNA metabolism (Venkatesh et al 2002;Yakimov et al 2017). Previous work revealed that RecX is also involved in regulating the Mycobacterium smegmatis stress response (Prasad et al 2019). However, the regulatory mechanisms of RecX have been less studied in the biocontrol bacterium L. enzymogenes.…”