title: Identification of the genes that contribute to lactate utilization in Helicobacter pylori.
abstract: Helicobacter pylori are Gram-negative, spiral-shaped microaerophilic bacteria etiologically related to gastric cancer. Lactate utilization has been implicated although no corresponding genes have been identified in the H. pylori genome. Here, we report that gene products of hp0137-0139 (lldEFG), hp0140-0141 (lctP), and hp1222 (dld) contribute to D- and L-lactate utilization in H. pylori. The three-gene unit hp0137-0139 in H. pylori 26695 encodes L-lactate dehydrogenase (LDH) that catalyzes the conversion of lactate to pyruvate in an NAD-dependent manner. Isogenic mutants of these genes were unable to grow on L-lactate-dependent medium. The hp1222 gene product functions as an NAD-independent D-LDH and also contributes to the oxidation of L-lactate; the isogenic mutant of this gene failed to grow on D-lactate-dependent medium. The parallel genes hp0140-0141 encode two nearly identical lactate permeases (LctP) that promote uptake of both D- and L-lactate. Interestingly an alternate route must also exist for lactate transport as the knockout of genes did not completely prevent growth on D- or L-lactate. Gene expression levels of hp0137-0139 and hp1222 were not enhanced by lactate as the carbon source. Expression of hp0140-0141 was slightly suppressed in the presence of L-lactate but not D-lactate. This study identified the genes contributing to the lactate utilization and demonstrated the ability of H. pylori to utilize both D- and L-lactate.
authors: Department of Medicine-Gastroenterology, Baylor College of Medicine and Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, United States of America; Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan.
authors: Shun
authors: S
authors: Iwatani
authors: Department of Medicine-Gastroenterology, Baylor College of Medicine and Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, United States of America; Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan.
authors: Hiroyuki
authors: H
authors: Nagashima
authors: Department of Medicine-Gastroenterology, Baylor College of Medicine and Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, United States of America.
authors: Rita
authors: R
authors: Reddy
authors: Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan.
authors: Seiji
authors: S
authors: Shiota
authors: Department of Medicine-Gastroenterology, Baylor College of Medicine and Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, United States of America.
authors: David Y
authors: DY
authors: Graham
authors: Department of Medicine-Gastroenterology, Baylor College of Medicine and Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, United States of America; Department of Environmental and Preventive Medicine, Oita University Faculty of Medicine, Oita, Japan.
authors: Yoshio
authors: Y
authors: Yamaoka
mesh_terms: D005798:Genes, Bacterial; D016480:Helicobacter pylori / Q000235:genetics / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism*
chemical_list: D019344:Lactic Acid