title: Proteomic characterization of the acid tolerance response in Lactobacillus delbrueckii subsp. bulgaricus CAUH1 and functional identification of a novel acid stress-related transcriptional regulator Ldb0677.
abstract: To overcome the deleterious effects of acid stress, Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) elicits an adaptive response to acid stress. In this study, proteomics approach complemented by transcriptional analysis revealed some cellular changes in L. bulgaricus CAUH1 during acid adaptation. We observed an increase of glycolysis-associated proteins, promoting an optimal utilization of carbohydrates. Also, rerouting of the pyruvate metabolism to fatty acid biosynthesis was observed, indicating a possible modification of the cell membrane rigidity and impermeability. In addition, expression of ribosomal protein S1 (RpsA) was repressed; however, the expression of EF-Tu, EF-G and TypA was up-regulated at both protein and transcript levels. This suggests a reduction of protein synthesis in response to acid stress along with possible enhancement of the translational accuracy and protein folding. It is noteworthy that the putative transcriptional regulator Ldb0677 was 1.84-fold up-regulated. Heterologous expression of Ldb0677 was shown to significantly enhance acid resistance in host strain Lactococcus lactis. To clarify its role in transcriptional regulation network, the DNA-binding specificity of Ldb0677 was determined using bacterial one-hybrid and electrophoretic mobility shift assay. The identification of a binding motif (SSTAGACR) present in the promoter regions of 22 genes indicates that it might function as a major regulator in acid stress response in L. bulgaricus.
authors.affiliation: Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Municipality, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, 100083, China.
authors.forename: Zhengyuan
authors.initials: Z
authors.lastname: Zhai
authors.forename: François P
authors.initials: FP
authors.lastname: Douillard
authors.forename: Haoran
authors.initials: H
authors.lastname: An
authors.forename: Guohong
authors.initials: G
authors.lastname: Wang
authors.forename: Xinghua
authors.initials: X
authors.lastname: Guo
authors.forename: Yunbo
authors.initials: Y
authors.lastname: Luo
authors.forename: Yanling
authors.initials: Y
authors.lastname: Hao
mesh_terms: D000136:Acid-Base Equilibrium; D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D016384:Consensus Sequence; D015964:Gene Expression Regulation, Bacterial; D048668:Lactobacillus delbrueckii / Q000502:physiology*; D020653:Peptide Elongation Factor G / Q000235:genetics / Q000378:metabolism; D010444:Peptide Elongation Factor Tu / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D020653:Peptide Elongation Factor G; D020543:Proteome; D014157:Transcription Factors; D010444:Peptide Elongation Factor Tu