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

Abstract

We have used RNASeq and qRT-PCR to study mRNA levels for all σ-factors in different Mycobacterium marinum strains under various growth and stress conditions. We also studied their levels in M. marinum from infected fish and mosquito larvae. The annotated σ-factors were expressed and transcripts varied in relation to growth and stress conditions. Some were highly abundant such as sigA, sigB, sigC, sigD, sigE and sigH while others were not. The σ-factor mRNA profiles were similar after heat stress, during infection of fish and mosquito larvae. The similarity also applies to some of the known heat shock genes such as the α-crystallin gene. Therefore, it seems probable that the physiological state of M. marinum is similar when exposed to these different conditions. Moreover, the mosquito larvae data suggest that this is the state that the fish encounter when infected, at least with respect to σ-factor mRNA levels. Comparative genomic analysis of σ-factor gene localizations in three M. marinum strains and Mycobacterium tuberculosis H37Rv revealed chromosomal rearrangements that changed the localization of especially sigA, sigB, sigD, sigE, sigF and sigJ after the divergence of these two species. This may explain the variation in species-specific expression upon exposure to different growth conditions.

The fused SnoaL_2 domain in the Mycobacterium tuberculosis sigma factor σJ modulates promoter recognition

“…Interestingly, M. tuberculosis ECF41 σ factor σ J has been reported to influence resistance to hydrogen peroxide-mediated oxidative stress ( 20 ). Another study on M. marinum σ factors under different stress conditions suggests the possible involvement of σ J in heat stress ( 21 ). The lack of an apparent anti-σ factor that is a receptor for redox stimuli made it interesting to explore whether the additional domain in σ J plays a role akin to an anti-σ factor.…”

Structural insights ofMycobacteriumGTPase-Obg and anti-sigma-F factor Usfx interaction

“…14 β-sheets (numbered [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Similarly, Usfx secondary structure is characterized by 3 α-helices (numbered i-iii) and 5 β-sheets (numbered i-v) (Table S2).…”

“…A number of sigma factors are reported in Escherichia coli ( E coli ) including σ 70 , σ 19 , σ 24 , σ 28 , σ 32 , σ 38 , and σ 54 . Among them, σ 70 and σ 54 families are well characterized . The MTB has 13 sigma factor genes, of which SigA is constitutively expressed and required essentially for survival .…”

“…Among them, σ 70 and σ 54 families are well characterized. 5 The MTB has 13 sigma factor genes, of which SigA is constitutively expressed and required essentially for survival. 6 SigF is another sigma factor, which is considered a stress response factor as its expression increases in MTB under stress conditions, such as nutrient starvation, cold shock, and antibiotics.…”

Sigma factor FaSigE positively regulates strawberry fruit ripening by ABA

“…Interestingly, SigE regulates gene expression specifically during the post-exponential growth phase of Synechococcus species (Gruber and Bryant 1998). Thus, as a cell surface stressrelated transcription factor, SigE is important for bacterial growth and stress resistance, with diverse effects on cell sporulation (Shuler et al 1995;Wong et al 1995;AlHinai et al 2014;Casonato et al 2014;Kirk et al 2014), granuloma formation (Giacomini et al 2006), phagocytosis by macrophages (Ando et al 2003), cell wall integrity (Paget et al 1999), fatty acid metabolism (Manganelli et al 2001), carotenoid biosynthesis (Hakkila et al 2013), nitrogen starvation and sugar catabolism (Osanai et al 2005a), and responses to various stresses, including acid (Bansal et al 2017), oxidative (Bagchi and Ghosh 2006;Pacheco et al 2012), heat (Pettersson et al 2015), and salt (Koskinen et al 2016) stresses.…”