title: Flavohaemoglobin HmpX: a new pathogenicity determinant in Erwinia chrysanthemi strain 3937.
abstract: Unlike wild-type Erwinia chrysanthemi strain 3937, which fully macerates inoculated Saintpaulia plants, HmpX- mutants produce necrotic lesions or no symptoms. The hmpX gene was sequenced and the corresponding protein sequence analysed. We show that HmpX belongs to a family of flavohaemoproteins (HMP), previously identified in two yeasts and in Escherichia coli. Comparisons of protein sequences at the secondary structure level by hydrophobic cluster analysis have shown that HmpX possesses two functional regions, a haemoglobin domain in its N-terminal part and a flavin reductase domain in its C-terminal part. In an HmpX- strain, the synthesis of pectate lyases, which are pathogenicity determinants in E. chrysanthemi, was reduced in conditions of low oxygen tension. Using gus fusion in hmpX, it was shown that hmpX transcription was induced in coculture with tobacco cells. A putative function for HmpX is discussed.
authors.affiliation: Laboratoire de pathologie végétale, INRA, INA P/G, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Favey
authors.forename: G
authors.initials: G
authors.lastname: Labesse
authors.forename: V
authors.initials: V
authors.lastname: Vouille
authors.forename: M
authors.initials: M
authors.lastname: Boccara
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D016974:Dickeya chrysanthemi / Q000235:genetics* / Q000472:pathogenicity*; D015870:Gene Expression; D005798:Genes, Bacterial; D006420:Hemeproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology; D010947:Plants, Toxic; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000382:microbiology; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D006420:Hemeproteins; C094007:hmpX protein, Bacteria