title: Overexpression of luxS cannot increase autoinducer-2 production, only affect the growth and biofilm formation in Streptococcus suis.
abstract: LuxS/AI-2 quorum sensing (QS) system involves the production of cell signaling molecules via luxS-based autoinducer-2 (AI-2). LuxS has been reported to plays critical roles in regulating various behaviors of bacteria. AI-2 is a byproduct of the catabolism of S-adenosylhomocysteine (SAH) performed by the LuxS and Pfs enzymes. In our previous study, the function of LuxS in AI-2 production was verified in Streptococcus suis (SS). Decreased levels of SS biofilm formation and host-cell adherence as well as an inability to produce AI-2 were observed in bacteria having a luxS mutant gene. In this study, the level of AI-2 activity exhibits a growth-phase dependence with a maximum in late exponential culture in SS. An SS strain that overexpressed luxS was constructed to comprehensively understand the function of AI-2. Overexpressed luxS was not able to increase the level of pfs expression and produce additional AI-2, and the bacteria were slower growing and produced only slightly more biofilm than the wild type. Thus, AI-2 production is not correlated with luxS transcription. luxS expression is constitutive, but the transcription of pfs is perhaps correlated with AI-2 production in SS.
authors: College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471003, China ; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China ; OIE Reference Laboratory for Swine Streptococcosis, Nanjing 210095, China.
authors: Yang
authors: Y
authors: Wang
authors: Li
authors: L
authors: Yi
authors: Zhicheng
authors: Z
authors: Zhang
authors: Hongjie
authors: H
authors: Fan
authors: Xiangchao
authors: X
authors: Cheng
authors: Chengping
authors: C
authors: Lu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D018441:Biofilms; D013437:Carbon-Sulfur Lyases / Q000235:genetics*; D017931:DNA Primers; D005798:Genes, Bacterial; D006714:Homoserine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D007783:Lactones; D053038:Quorum Sensing; D060888:Real-Time Polymerase Chain Reaction; D017011:Streptococcus suis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D007783:Lactones; C091088:N-octanoylhomoserine lactone; D006714:Homoserine; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria