Identification and expression of stressosomal proteins inMycobacterium marinumunder various growth and stress conditions

Abstract

Like other bacteria, Mycobacterium spp. have developed different strategies in response to environmental changes such as nutrient limitations and other different stress situations. We have identified candidate genes (rsb genes) from Mycobacterium marinum involved in the regulation of the activity of the alternative sigma factor, σ(F) . This is a homolog of the master regulator of general stress response, σ(B) , and the sporulation-specific sigma factor, σ(F) , in Bacillus subtilis. The organization of these genes in M. marinum and B. subtilis is similar. Transcriptome and qRT-PCR data show that these genes are indeed expressed in M. marinum and that the levels of expression vary with growth phase and exposure to stress. In particular, cold stress caused a significant rise in the expression of all identified rsb and sigF genes. We discuss these data in relation to what is currently known for other Mycobacterium spp.

Comparative Sigma Factor-mRNA Levels in Mycobacterium marinum under Stress Conditions and during Host Infection

“…This appeared not to be the case for M . marinum in which the level of sigF mRNA was higher in exponentially growing cell while there was no change after oxidative stress (this report; see also [ 21 ]). Chromosomal rearrangements may therefore have an impact on the expression of sigF .…”

“…These differences may be because the RNASeq σ-factor level were estimated relative to the total rRNA depeleted RNA while the qRT-PCR values were expressed relative to 16S rRNA. Another reason could be RNA degradation (see also [ 21 ]).…”

“…marinum infects a host (see below). Hence we decided to analyze the σ-factor mRNA levels in cells after exposure to different stress conditions (see Materials and Methods ; [ 21 ]). These were: i) nitric oxide, ii) mitomycin C, iii) the antibiotic isoniazid, iv) osmotic stress, v) oxidative stress, vi) acidic stress, vii) starvation, viii) heat stress, ix) cold stress, and x) microaerobic stress (depletion of oxygen).…”

“…marinum 1218S, which is a smooth colony variant of M . marinum 1218R ([ 22 ]; see [ 14 , 21 ] for details, see also S2 Table ) and it was used for comparison. M .…”

Draft Genome Sequence of Saccharopolyspora rectivirgula

“…Genomic DNA was isolated by lysis using bead beating in equal volumes DNAzol (Invitrogen) and Tris-EDTA (TE) buffer (10 mM Tris [pH 7.9] and 1 mM EDTA) using conditions previously described (14), and the pellet was resuspended in TE buffer. The DNA was treated with RNase A and proteinase K according to standard protocols.…”