Eukaryotic-like Adenylyl Cyclases in Mycobacterium tuberculosis H37Rv

Abstract

Screening the Mycobacterium tuberculosisMycobacterium tuberculosis H37Rv, the etiologic agent of tuberculosis, accounts for more human causalities than any other single infection (1). Pathogenesis of M. tuberculosis is not attributable to any single gene product. In other bacterial pathogens such as Bordetella pertussis and Bacillus anthrax, adenylyl cyclase, the enzyme responsible for the synthesis of adenosine 3Ј,5Ј-monophosphate (cAMP), plays a pivotal role in pathogenesis (2). The secreted form of adenylyl cyclase from B. pertussis (3) and B. anthrax (4) invades a variety of eukaryotic cells and is activated by the intracellular calmodulin of the host. This results in the unregulated conversion of ATP to a supraphysiological concentration of cAMP, which in turn has a profound effect on the metabolism and immune function of the host cell (5, 6). Thus, in infections caused by B. pertussis and B. anthrax, adenylyl cyclase plays a critical role in the onset of the disease. To examine whether adenylyl cyclase in M. tuberculosis has any role in infection, we report in this paper the cloning of cya gene from M. tuberculosis H37Rv, heterologous expression in Escherichia coli, and characterization of adenylyl cyclase (Mtb AC, 1

cAMP synthesis and degradation by phagosomes regulate actin assembly and fusion events: consequences for mycobacteria

“…One caveat here is that although the main effects are likely to be due to activity of macrophage enzymes we cannot rule out the fact that the effectors and/or inhibitors we used may also target the equivalent enzymes known to be expressed by the mycobacteria themselves (Shenoy et al, 2005;Lowrie et al, 1975;Castro et al, 2005;Cann et al, 2003;Reddy et al, 2001). Complex effects of modulating cAMP levels in mycobacterium-infected macrophages have been described in many studies making it difficult to provide a simple model (e.g.…”

“…This system mediates a plethora of cellular functions with extensive 'cross-talk' occurs between it and other signaling networks throughout cells (Beavo and Brunton, 2002;Antoni, 2000;Ellerbroek et al, 2003;Frisch, 2000;Houslay and Kolch, 2000;Tasken and Anandahl, 2004;Wong and Scott, 2004;Houslay, 1998;Housley and Milligan, 1997;Howe and Juliano, 2000). Increases in cAMP levels generally compromise the bactericidal activity of the host immune system (Bengis-Garber and Gruener, 1996;Gueirard et al, 1998;Khelef et al, 1993;Reddy et al, 2001). Many pathogens have taken advantage of this phenomenon and evolved mechanisms to elevate intracellular cAMP levels in both macrophages (Gross et al, 2003;Hanski, 1989) and neutrophils (Confer and Eaton, 1982;Gross et al, 2003;Hanski, 1989;Nathan, 2003) -evidently to facilitate their survival within phagosomes.…”

Identification of Cyclic AMP-Regulated Genes in Mycobacterium tuberculosis Complex Bacteria under Low-Oxygen Conditions

“…All candidate open reading frames contained a cyclase homology domain associated with one of a variety of cytoplasmic, receptor-type, and integral membrane structural motifs (35). Two of these genes (Rv1625c and Rv2435c) belong to the mammalian type adenylyl cyclase grouping, and both enzymes are active (19,28,35,50,54). Functionality has also been shown for the mycobacterial cyclases Rv1264, Rv1318c, Rv1319c, Rv1320c, and Rv3645 (6,27).…”

A Defined Subset of Adenylyl Cyclases Is Regulated by Bicarbonate Ion

“…We expressed amino acids 160 to 353 of cyaB as a recombinant protein (cyaB ) that contained a threonine residue (T293) at the position corresponding to cyaB1 T721 ( Figure 1A). cyaB 160 Mycobacterium tuberculosis H37Rv is a gram-negative bacterium and important human pathogen for which the genome has revealed a number of putative class III ACs (15,21,22). We expressed two ACs that contain either a threonine (amino acids 356-535 of Rv1319c) or an aspartate (Rv1264 holoenzyme) at the position corresponding to T721 of cyaB1 ( Figure 1A).…”