title: PlsX deletion impacts fatty acid synthesis and acid adaptation in Streptococcus mutans.
abstract: Streptococcus mutans, one of the primary causative agents of dental caries in humans, ferments dietary sugars in the mouth to produce organic acids. These acids lower local pH values, resulting in demineralization of the tooth enamel, leading to caries. To survive acidic environments, Strep. mutans employs several adaptive mechanisms, including a shift from saturated to unsaturated fatty acids in membrane phospholipids. PlsX is an acyl-ACP : phosphate transacylase that links the fatty acid synthase II (FASII) pathway to the phospholipid synthesis pathway, and is therefore central to the movement of unsaturated fatty acids into the membrane. Recently, we discovered that plsX is not essential in Strep. mutans. A plsX deletion mutant was not a fatty acid or phospholipid auxotroph. Gas chromatography of fatty acid methyl esters indicated that membrane fatty acid chain length in the plsX deletion strain differed from those detected in the parent strain, UA159. The deletion strain displayed a fatty acid shift similar to WT, but had a higher percentage of unsaturated fatty acids at low pH. The deletion strain survived significantly longer than the parent strain when cultures were subjected to an acid challenge of pH 2.5.The ΔplsX strain also exhibited elevated F-ATPase activity at pH 5.2, compared with the parent. These results indicate that the loss of plsX affects both the fatty acid synthesis pathway and the acid-adaptive response of Strep. mutans.
authors: Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors: Benjamin
authors: B
authors: Cross
authors: Center for Oral Biology in the Eastman Institute for Oral Health, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors: Ariana
authors: A
authors: Garcia
authors: Center for Oral Biology in the Eastman Institute for Oral Health, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors: Roberta
authors: R
authors: Faustoferri
authors: Robert G
authors: RG
authors: Quivey
mesh_terms: D000143:Acids / Q000633:toxicity*; D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000235:genetics*; D002462:Cell Membrane / Q000737:chemistry; D005227:Fatty Acids / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D017353:Gene Deletion; D010743:Phospholipids / Q000378:metabolism; D013295:Streptococcus mutans / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*
chemical_list: D000143:Acids; D001426:Bacterial Proteins; D005227:Fatty Acids; D010743:Phospholipids; C088150:plsX protein, bacteria