Cyclic di-GMP: a second messenger required for long-term survival, but not for biofilm formation, in Mycobacterium smegmatis

Abstract

Cyclic di-GMP (c-di-GMP) plays an important role in bacterial adaptation to enable survival in changing environments. It orchestrates various pathways involved in biofilm formation, changes in the cell surface, host colonization and virulence. In this article, we report the presence of c-di-GMP in Mycobacterium smegmatis, and its role in the long-term survival of the organism. M. smegmatis has a single bifunctional protein with both GGDEF and EAL domains, which show diguanylate cyclase (DGC) and phosphodiesterase (PDE)-A activity, respectively, in vitro. We named this protein MSDGC-1. Deletion of the gene encoding MSDGC-1 did not affect growth and biofilm formation in M. smegmatis, but long-term survival under conditions of nutritional starvation was affected. Most of the proteins that contain GGDEF and EAL domains have been demonstrated to have either DGC or PDE-A activity. To gain further insight into the regulation of the protein, we cloned the individual domains, and tested their respective activities. MSDGC-1, the full-length protein, is required for activity, as its GGDEF and EAL domains are inactive when separated.

Analysis of the Borrelia burgdorferi Cyclic-di-GMP-Binding Protein PlzA Reveals a Role in Motility and Virulence

“…The activities of these cyclase and phosphodiesterase enzymes are often regulated by changing physiological conditions. c-di-GMP has been implicated in the regulation of diverse bacterial properties, including biosynthesis of adhesins and exopolysaccharide matrix for biofilm formation, different forms of motility, long-term survival, and response to environmental stresses, in addition to production of virulence factors and to virulence (14,29,39,76,88,96). These cellular functions regulated by c-di-GMP often utilize multiple receptors and signaling mechanisms.…”

Characterization of NrnA homologs from Mycobacterium tuberculosis and Mycoplasma pneumoniae

“…We had pointed out before that NrnA might play a role in the degradation of pGpG, a linear dinucleotide resulting from the degradation of cyclic di-GMP by phosphodiesterase. Cyclic di-GMP was shown to play an important role in the long-term survival of M. smegmatis (Kumar and Chatterji 2008), a faster-growing, nonpathogenic species that is commonly used as model system for pathogenic mycobacterial pathogens. The preference of Rv2837c for 2-mers is in agreement with a potential role for this enzyme in the degradation of pGpG.…”

Cyclic Di-GMP Phosphodiesterases RmdA and RmdB Are Involved in Regulating Colony Morphology and Development in Streptomyces coelicolor

“…The c-di-GMP signaling pathways are present in many Gram-positive bacteria (9), but functional studies have been done only in mycobacteria, where c-di-GMP signaling appears to play a relatively limited role and is involved in long-term survival (32). Recent reports uncovered the involvement of c-di-GMP in the development of the Gram-positive actinomycete Streptomyces coelicolor (17,59).…”

“…It is often possible to predict the enzymatic activity of the GGDEF-EAL proteins based on conservation of the amino acids essential for catalysis. However, some enzymes are bifunctional, and their prevailing activity depends on the input signal (20,32,57).…”