title: Trehalose is required for growth of Mycobacterium smegmatis.
abstract: Mycobacteria contain high levels of the disaccharide trehalose in free form as well as within various immunologically relevant glycolipids such as cord factor and sulfolipid-1. By contrast, most bacteria use trehalose solely as a general osmoprotectant or thermoprotectant. Mycobacterium tuberculosis and Mycobacterium smegmatis possess three pathways for the synthesis of trehalose. Most bacteria possess only one trehalose biosynthesis pathway and do not elaborate the disaccharide into more complex metabolites, suggesting a distinct role for trehalose in mycobacteria. We disabled key enzymes required for each of the three pathways in M. smegmatis by allelic replacement. The resulting trehalose biosynthesis mutant was unable to proliferate and enter stationary phase unless supplemented with trehalose. At elevated temperatures, however, the mutant was unable to proliferate even in the presence of trehalose. Genetic complementation experiments showed that each of the three pathways was able to recover the mutant in the absence of trehalose, even at elevated temperatures. From a panel of trehalose analogs, only those with the native alpha,alpha-(1,1) anomeric stereochemistry rescued the mutant, whereas alternate stereoisomers and general osmo- and thermoprotectants were inactive. These findings suggest a dual role for trehalose as both a thermoprotectant and a precursor of critical cell wall metabolites.
authors.affiliation: Departments of Chemistry and Molecular, School of Public Health and Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Woodruff
authors.forename: Brian L
authors.initials: BL
authors.lastname: Carlson
authors.forename: Bunpote
authors.initials: B
authors.lastname: Siridechadilok
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Pratt
authors.forename: Ryan H
authors.initials: RH
authors.lastname: Senaratne
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Mougous
authors.forename: Lee W
authors.initials: LW
authors.lastname: Riley
authors.forename: Spencer J
authors.initials: SJ
authors.lastname: Williams
authors.forename: Carolyn R
authors.initials: CR
authors.lastname: Bertozzi
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005816:Genetic Complementation Test; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D015394:Molecular Structure; D009154:Mutation; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D013696:Temperature; D014199:Trehalose / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D014199:Trehalose; D005964:Glucosyltransferases; C099692:trehalose synthase; C023180:trehalose-6-phosphate synthase