The OtsAB pathway is essential for trehalose biosynthesis in Mycobacterium tuberculosis.
The disaccharide trehalose is the major free sugar in the cytoplasm of mycobacteria; it is a constituent of cell wall glycolipids, and it plays a role in mycolic acid transport during cell wall biogenesis. The pleiotropic role of trehalose in the biology of Mycobacterium tuberculosis and its absence from mammalian cells suggests that its biosynthesis may provide a useful target for novel drugs. However, there are three potential pathways for trehalose biosynthesis in M. tuberculosis, and the aim of the present study was to introduce mutations into each of the pathways to determine whether or not they are functionally redundant. The results show that the OtsAB pathway, which generates trehalose from glucose and glucose-6-phosphate, is the dominant pathway required for M. tuberculosis growth in laboratory culture and for virulence in a mouse model. Of the two otsB homologues annotated in the genome sequence of M. tuberculosis, only OtsB2 (Rv3372) has a functional role in the pathway. OtsB2, trehalose-6-phosphate phosphatase, is strictly essential for growth and provides a tractable target for high throughput screening. Inactivation of the TreYZ pathway, which can generate trehalose from alpha-1,4-linked glucose polymers, had no effect on the growth of M. tuberculosis in vitro or in mice. Deletion of the treS gene altered the late stages of pathogenesis of M. tuberculosis in mice, significantly increasing the time to death in a chronic infection model. Because the TreS enzyme catalyzes the interconversion of trehalose and maltose, the mouse phenotype could reflect either a requirement for synthesis of additional trehalose or, conversely, a requirement for breakdown of stored trehalose to liberate free glucose.
Murphy
Helen N
HN
Centre for Molecular Microbiology and Infection, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom.
Stewart
Graham R
GR
Mischenko
Vladimir V
VV
Apt
Alexander S
AS
Harris
Richard
R
McAlister
Mark S B
MS
Driscoll
Paul C
PC
Young
Douglas B
DB
Robertson
Brian D
BD
D000818:Animals; D019843:Archaeal Proteins / Q000378:metabolism; D002384:Catalysis; D049109:Cell Proliferation; D002473:Cell Wall / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004187:Disaccharides / Q000737:chemistry; D004195:Disease Models, Animal; D005947:Glucose / Q000737:chemistry / Q000378:metabolism; D019298:Glucose-6-Phosphate / Q000378:metabolism; D005964:Glucosyltransferases / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009169:Mycobacterium tuberculosis / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry; D013997:Time Factors; D014199:Trehalose / Q000737:chemistry* / Q000378:metabolism; D014376:Tuberculosis / Q000382:microbiology; D000516:alpha-Amylases / Q000378:metabolism
D019843:Archaeal Proteins; D017931:DNA Primers; D004187:Disaccharides; D011994:Recombinant Proteins; D019298:Glucose-6-Phosphate; D014199:Trehalose; D005964:Glucosyltransferases; C499532:trehalosyl dextrin-forming enzyme, Sulfolobus solfataricus; C023180:trehalose-6-phosphate synthase; C023178:trehalose-phosphatase; D010744:Phosphoric Monoester Hydrolases; D000516:alpha-Amylases; D005947:Glucose