**7. Conclusions**

Acidity is a condition that is encountered by both environmental mycobacteria and mycobacteria of the *Mycobacterium tuberculosis* complex. Mycobacteria are hypothesized to possess a large degree of innate resistance to acidic stress as well as an incredible ability to make adaptive changes to withstand acidic environments. This is certainly true for environmental mycobacteria which can survive in extreme conditions. It is interesting to speculate that pathogenic mycobacteria have evolved from environmental mycobacteria and maintain some intrinsic acid resistance as well as a rich and varied ability to respond adaptively to acidic stress. These pathogenic mycobacteria for the most part will never encounter the external environment, yet they are well suited to withstand the hostile environment within the phagosome of macrophages as well as the acidic centers of caseating granulomas. Drug targets against genes necessary to survive acidic stress may be developed to eliminate *M. tuberculosis* present within acidic environments including conditions that favor dormancy.

### **8. References**


control acid responsive genes. The kinetics of the response will be different for each regulator and as a consequence depend on the exact nature of the signal that the regulator senses. Signals may be a direct or indirect consequence of acidic damage. These questions will be important when considering acid responsive genes as drug targets. Inhibition of a gene expressed early may block establishment of infection but be ineffective during chronic infection. Likewise a drug against a gene upregulated at 3 weeks may be effective against a

Acidity is a condition that is encountered by both environmental mycobacteria and mycobacteria of the *Mycobacterium tuberculosis* complex. Mycobacteria are hypothesized to possess a large degree of innate resistance to acidic stress as well as an incredible ability to make adaptive changes to withstand acidic environments. This is certainly true for environmental mycobacteria which can survive in extreme conditions. It is interesting to speculate that pathogenic mycobacteria have evolved from environmental mycobacteria and maintain some intrinsic acid resistance as well as a rich and varied ability to respond adaptively to acidic stress. These pathogenic mycobacteria for the most part will never encounter the external environment, yet they are well suited to withstand the hostile environment within the phagosome of macrophages as well as the acidic centers of caseating granulomas. Drug targets against genes necessary to survive acidic stress may be developed to eliminate *M. tuberculosis* present within acidic environments including

Abdallah A, Gey van Pittius N, Champion P, Cox J, Luirink J, Vandenbroucke-Grauls C,

Abramovitch RB, Rohde KH, Hsu F, and Russell. 2011. aprABC: a *Mycobacterium tuberculosis*

Aguilar D, Infante E, Martin C, Gormly E, Gicquel B, and Hernandez Pando R. 2006.

Armstrong JA, and Hart D. 1971. Response of cultured macrophages to Mycobacterium

Behr MA, Wilson MA, Gill WP, Salamon H, Schoolnik GK, Rane S, and Small PM. 1999.

Biswas T, Small J, Vandal O, Odaira T, Deng H, Ehrt S, and Tsodikov OV. 2010. Structural

Bland CS, Ireland JM, Lozano E, Alvarez ME, and Primm TP. 2005. Mycobacterial ecology of the Rio Grande. Applied and Environmental Microbiology. 71(10):5719-5727.

SO2 strain. Clinical and Experimental Immunology. 147:330-338.

Appelmelk B, and Bitter W. 2007. Type VII secretion-mycobacteria show the way.

complex-specific locus that modulated pH-driven adaptation to the macrophage

Immunological responses and protective immunity against tuberculosis conferred by vaccination of Balb/C mice with the attenuated *Mycobacteria tuberculosis* (*phoP*)

*tuberculosis* with observations on fusion of lysosomes with phagosomes. Journal of

Comparative genomics of BCG vaccines by whole genome DNA microarray.

insight into serine protease Rv3671c that protects *M. tuberculosis* from oxidative and

chronic infection but be unable to prevent establishment of infection.

Nature Reviews in Microbiology. 5: 883-891.

Experimental Medicine. 134(3): 713-740.

acidic stress. Structure. 18(10): 13353-1363.

Science 284:1520-1523.

phagososme. Molecular Microbiology. 80(3):678-694.

**7. Conclusions** 

conditions that favor dormancy.

**8. References** 


Response of Mycobacterial Species to an Acidic Environment 101

Raynaud C, Papavinasasundaram KG, Speight RA, Springer B, Sander P, Bottger EC,

Richter L, and Saviola B. 2009. The *lipF* promoter of *Mycobacterium tuberculosis* is

Rohde K, Yates RM, Purdy GE, and Russell DG. 2007. *Mycobacterium tuberculosis* and the environment within the phagosome. Immunological Reviews. 219: 37-54. Rose L, Kaufmann S, and Daugelat S. 2004. Involvement of *Mycobacterium smegmatis*

Roxas B, and Li Q. 2009. Acid stress response of a mycobacterial proteome: insights from gene ontology analysis. International Journal of Clinical Medicine. 2:309-328. Ryndak M, Wang S, and Smith I. 2008. PhoP, a key player in *Mycobacterium tuberculosis*

Santos R, Fernandes J, Fernandes N, Oliveira F, and Cadete M. 2007. *Mycobacterium* 

Saviola B, Seabold R, and Schleif R. 1998 Arm-domain interactions in AraC. Journal of

Saviola B, Woolwine S, and Bishai W. 2002. Isolation of acid-inducible genes of

Schaible RH, Sturgill-Koszycki S, Schlesinger PH, and Russell DG. 1998. Cytokine activation

environment. The Journal of Experimental Medicine. 198(5):693-704. Simeone R, Bottai D, and Brosch R. 2009. ESX/type VII secretion systems and their role in host-pathogen interaction. Current Opinion in Microbiology. 12:4-10. Singh A, Gupta R, Vishwakarma RA, Narayanan PR, Paramasivan CN, Ramanathan VD,

of *Mycobacterium tuberculosis*. Molecular Microbiology. 46(1):191-201. Rhode KH, Abramovitch RB, and Russell DG. 2007. *Mycobacterium tuberculosis* invasion of

and Microbe. 2:352-364.

Infection. 6:965-971.

Microbiological Research. 164(2):228-32 (2009)

virulence. Trends in Microbiology. 16(11):528-534.

Environmental Microbiology. 73(15) 5071-5073.

technology. Infection and Immunity. 71(3): 1379-1388.

pigs. Journal of Bacteriology. 187(12):4173-4186.

Bacteriology. 190(4): 1317-1328.

Microbiology. 152: 2717-2725.

Molecular Biology. 278: 539-548.

Colston MJ, and Draper P. 2002. The functions of OMpATb a pore- forming protein

macrophages: linking bacterial gene expression to environmental cues. Cell Host

upregulated specifically by acidic pH but not by other stress conditions.

undecaprenyl phosphokinase in biofilm and smegma formation. Microbes and

*parascrofulaceum* in acidic hot springs in Yellowstone National Park. Applied

*Mycobacterium tuberculosis* with the use of recombinase based in vivo expression

leads to acidification and increases maturation of *Mycobacterium avium*-containing phagosomes in murine macrophages. Journal of Immunology. 160: 1290-1296. Schnappinger D, Ehrt S, Voskuil MI, Liu Y, mangan JA, Monahan IM, Dolganov G, Efron B,

Butcher PD, Nathan C, and Schoolnik GK. 2003. Transcriptional adaptation of *Mycobacterium tuberculosis* within macrophages: insights into the phagosomal

and Tyagi AK. 2005. Requirement of *mymA* operon for appropriate cell wall ultrastructure and persistence of *Mycobacterium tuberculosis* in the spleens of guinea

adjacent PhoP binding sites is influenced by protein phosphorylation. Journal of

PE. 2006. Identification of a diacylglycerol acyltransferase gene involved in accumulation of triacyglycerol in Mycobacterium tuberculosis under stress.

Sinha A, Gupta S, Bhutani S, Pathak A, and Sarkar D. 2008. PhoP-PhoP interaction at

Sirakova TD, Dubey VS, Deb C, Daniiel J, Korotkova TA, Abomoelak B, and Kolattukudy


Kirschner RA, Parker BC and Fakinham JO. 1992. Epidemiology of infection by

Krischner RA, Parker BC, and Falkinham JO. 1999. Humic and fluvic acids stimulate growth

Lee JS, Krause R, Schreiber J, Mollenkobf H, Kowall J, Stein R, Jeon B, Kwak J, Song M,

Livanainen E, Martikainen PJ, Vaananen P, and Katila ML. 1999. Environmental factors

Lobell R, and Schleif R. 1990. DNA looping and unlooping by AraC Protein. Science. 250:

Low KL, Rao PSS, Shui G, Bendt AK, Pathe K, Dick T, and Wenk MR. 2009. Triacylglycerol

MackMicking JD, Taylor GA, and McKinney JD. 2003. Immune control of tuberculosis in

Martin C, Williams A, Hernandez-Pando R, Cardona PJ, Gormley E, Bordat Y, Soto CY,

Mostowy S, Cleto C, Sherman DR, and Behr MA. 2004. The *Mycobacterium tuberculosis*

Newton JA, Weiss PJ, Bowler WA, and Oldfield EC. 1993. Soft-tissue Infection due to

Niederweis M, Danilchanka O, Huff J, Hoffmann C, and Engelhardt H. 2010. proteins.

O'Brien LM, Gordon SV, Roberts IS, and Andrew PW. 1996. Response of *Mycobacterium* 

Perez E, Samper S, Bordas Y, Guilhot C, Gicquel B, and Martin C. 2001. An essential role for

Pym AS, Brodin P, Brosch R, Huerre M, and Cole ST. 2002. Loss of RD1 region contributed

Raghavan S, Manzanillo P, Chan K, Dovey K, and Cox JS. 2008. Secreted transcription factor

*Mycobacterium smegmatis*: Report of Two Cases. Clinical Infectious Disease.16:531-533.

*phoP* in *Mycobacterium tuberculosis* virulence. Molecular Micrbiology. 41(1):179-187. Portales F, and Pattyn SR. 1982. Growth of mycobacteria in relation to pH of the medium.

to the attenuation of the live tuberculosis vaccine *Mycobacterium bovis* BCG and

complex transcriptome of attenuation. Tuberculosis. 84:197-204.

*smegmatis* to acid stress. FEMS Microbiology Letters. 139:11-17.

*Mycobacterium microti*. Molecular Microbiology. 46: 709-717.

controls *Mycobacterium tuberculosis* virulence. Nature. 454:717-721.

of *Mycobacterium avium*. FEMS Microbiology Ecology. 30:327-332.

*tuberculosis* H37Ra strain. Cell Host and Microbe 3:97-103.

IFN-�-inducible LRG 47. Science. 302:654-659.

of Respiratory Disease. 1145:271-275.

Microbiology. 86:673-681.

Cambridge, United Kingdom.

Trends Microbiol.18(3):109-16.

Annals of Microbiology. 133:213-221.

528-532.

5037-5043.

nontuberculous mycobacteria. X. *Mycobacterium avium*, *Mycobacterium intracellulare*, and *Mycobacterium scrofulaceum* in acid brown-water swamps of the Southeastern United States and their association with environmental variables. American Review

Patron JP, Jorg S, Roh K, Cho S, and Kaufman S. 2008. Mutation in the transcriptional regulator PhoP contributes to avirulence of *Mycobacterium* 

affecting the occurrence of mycobacteria in brook sediments. Journal of Applied

utilization is required for regrowth of in vitro hypoxic nonreplicating *Mycobacterium bovis* bacillus Calmette-Guerin. Journal of Bacteriology. 191(16):

Clark SO, Hatch GJ, Aguilar D, Ausina V, and Gicquel B. 2006. The live attenuated *M. tuberculosis phoP* strain is more attenuated than BCG and confers protective immunity against tuberculosis in mice and guinea pigs. Vaccine. 24:3408-3419. Metchnikoff E. 1905 Immunity to infective disease, p. 182. Cambridge University Press,


**5** 

*Mexico* 

**Mycobacterium Tuberculosis** 

Mario Alberto Flores-Valdez1, Jeannette Barba2 and Angel H. Alvarez1

**1.1 Cyclic Adenosine Monophosphate (cAMP) metabolism in mycobacteria** 

**1.1.1 General aspects of Adenylyl Cyclases and their presence in** *M. tuberculosis*

Adelynate cyclases (ACs), which catalyze synthesis of cAMP from ATP and yield pyrophosphate as a by-product, can be classified into four different classes according to their common features: Class I cyclases, related to enterobacterial adenylate cyclases; Class II, toxic adenylate cyclases isolated from bacterial pathogens; Class III, a large and probably ancient class that comprises cyclases from both eukaryotes and prokaryotes and is strongly related to guanylate cyclases; and Class IV, with mainly one example that differs entirely

In class I ACs (the enterobacterial type) no long stretch of hydrophobic amino acid residues is present to explain the membrane-bound localization of the adenylate cyclases. In all cases, the proteins are very rich in cysteine residues, an uncommon feature for proteins located in the cytoplasm or at the cytoplasmic border of the membrane. They are also rich in histidine residues, which could indicate that metal ions take part in the folding and/or activity of the

Class II ACs (the calmodulin-activated toxic class) is represented by *Bordetella pertussis* adenylate cyclase. It is synthesized as a large bifunctional polypeptide chain of 1706 amino acid residues. The N-terminal segment of the protein (400 residues) alone displays calmodulin-activated adenylate cyclase activity, whereas the rest of the molecule is responsible for hemolytic activity and for transporting the toxin. After attempts to isolate other members of this class, several examples of similar proteins have now been discovered in *Bacillus anthracis*, *Pseudomonas aeruginosa*, and in Ye*rsinia* species. Comparison of the catalytic regions of the *B. pertussis* and *B. anthracis* adenylate cyclases identified four conserved regions that are involved in catalysis, calmodulin binding and activation. The first region comprises a sequence, Gly-XXXX-Gly(Ala)-Lys-Ser, similar to the nucleotidebinding motif found in many ATP- or GTP-binding proteins. Analysis of the region conserved between the *B. anthracis* and *B. pertussis* enzymes, indicates that these proteins

**1. Introduction** 

from all other classes (McCue *et al.*, 2000).

polypeptide chain (Mock *et al.*, 1991).

**genomes** 

*1Biotecnología Médica y Farmacéutica, CIATEJ, Guadalajara, Jalisco,* 

*2CUCBA, Universidad de Guadalajara, Guadalajara, Jalisco,* 

**Signaling via c-AMP** 

