title: Uptake of N,N'-diacetylchitobiose [(GlcNAc)2] via the phosphotransferase system is essential for chitinase production by Serratia marcescens 2170.
abstract: The chiR gene of Serratia marcescens 2170, encoding a LysR-type transcriptional activator, was identified previously as an essential factor for expression of chitinases and a chitin-binding protein, CBP21. To identify other genes that are essential for chitinase production, transposon mutagenesis with mini-Tn5Km1 was carried out, and 25 mutants that were unable to produce chitinases and CBP21 were obtained. Analysis of the mutated gene of one of the mutants, N22, revealed the presence of a pts operon in this bacterium, and a mutation was found in ptsI in the operon. In addition to its inability to produce chitinase, N22 did not grow well on N-acetyl-D-glucosamine (GlcNAc), (GlcNAc)(2), and some other carbon sources, most of which were phosphotransferase system (PTS) sugars. Thus, the inability to produce chitinase was assumed to be caused by the defect in uptake of (GlcNAc)(2) via the PTS, considering that (GlcNAc)(2) is the minimal substrate for chitinase induction and the major product of chitin hydrolysis by chitinases of this bacterium. To confirm this assumption, the chb operon, encoding the (GlcNAc)(2)-specific enzyme II permease, was cloned by reference to its Escherichia coli counterpart, and the Serratia chb operon was shown to comprise chbB, chbC, bglA, chbR, and chbG. Disruption of chbC drastically reduced production of chitinases and CBP21 and impaired growth on colloidal chitin. These results indicate that uptake of (GlcNAc)(2) is mediated by the PTS and that the (GlcNAc)(2)-specific enzyme II permease constitutes its major pathway. Since (GlcNAc)(2) uptake is essential for induction of chitinases and CBP21 production, (GlcNAc)(2) appears to be the key molecule in recognition and utilization of chitin by S. marcescens.
authors.affiliation: Department of Biosystem Science, Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Uchiyama
authors.forename: Ryousuke
authors.initials: R
authors.lastname: Kaneko
authors.forename: Junko
authors.initials: J
authors.lastname: Yamaguchi
authors.forename: Akane
authors.initials: A
authors.lastname: Inoue
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yanagida
authors.forename: Naoki
authors.initials: N
authors.lastname: Nikaidou
authors.forename: Miguel
authors.initials: M
authors.lastname: Regue
authors.forename: Takeshi
authors.initials: T
authors.lastname: Watanabe
mesh_terms: D002686:Chitin / Q000378:metabolism; D002688:Chitinases / Q000096:biosynthesis* / Q000235:genetics; D004251:DNA Transposable Elements; D004187:Disaccharides / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D012706:Serratia marcescens / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D004251:DNA Transposable Elements; D004187:Disaccharides; D002686:Chitin; C010913:N,N-diacetylchitobiose; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D002688:Chitinases