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Biomedical subjects

B Staskawicz

Publications and source records attributed to B Staskawicz.

10 recordsLinked to original sources
PubMed2000

Disruption of signaling by Yersinia effector YopJ, a ubiquitin-like protein protease.

Homologs of the Yersinia virulence effector YopJ are found in both plant and animal bacterial pathogens, as well as plant symbionts. These YopJ family members were shown to act as cysteine proteases. The catalytic triad of the protease was required for inhibition of the mitogen-activated protein kinase (MAPK) and nuclear factor kappaB (NF-kappaB) signaling in animal cells and for induction of localized cell death in plants. The substrates for YopJ were shown to be highly conserved ubiquitin-like molecules, which are covalently added to numerous regulatory proteins. YopJ family members exert their pathogenic effect on cells by disrupting this posttranslational modification.

Amino Acid Sequence↗
PubMed1997

Signaling in plant-microbe interactions.

Analysis of viral and bacterial pathogenesis has revealed common themes in the ways in which plants and animals respond to pathogenic agents. Pathogenic bacteria use macromolecule delivery systems (types III and IV) to deliver microbial avirulence proteins and transfer DNA-protein complexes directly into plant cells. The molecular events that constitute critical steps of plant-pathogen interactions seem to involve ligand-receptor mechanisms for pathogen recognition and the induction of signal transduction pathways in the plant that lead to defense responses. Unraveling the molecular basis of disease resistance pathways has laid a foundation for the rational design of crop protection strategies.

Animals↗
PubMed1996

Identification of a new Arabidopsis disease resistance locus, RPs4, and cloning of the corresponding avirulence gene, avrRps4, from Pseudomonas syringae pv. pisi.

A molecular genetic approach was used to study the interaction between Arabidopsis and an avirulence gene from Pseudomonas syringae pv. pisi. P. syringae pv. pisi strain 151 induces a hypersensitive response (HR) when inoculated on the Arabidopsis accession Po-1. A genomic cosmid library was constructed from DNA from P. syringae pv. pisi strain 151 and a cosmid was identified that causes the normally virulent P. syringae pv. tomato strain DC3000 to induce an HR on Po-1. The cosmid was subcloned and a 1.2-kb DNA fragment conferring avirulence activity was sequenced. The single significant open reading frame within the 1.2-kb fragment was designated avrRps4. An avrRps4-specific probe hybridizes to DNA from all P. syringae pv. pisi strains tested. P. syringae strains carrying avrRps4 induces an HR on specific accessions of both Arabidopsis and soybean. Arabidopsis accession Ws-0 is resistant to DC3000(avrRps4), whereas accession RLD is susceptible. Resistance segregates as a single dominant locus in a genetic cross between Ws-0 and RLD. This disease resistance locus, RPS4, was mapped to chromosome 5 between the molecular markers sAT2105 and KG-8.

Amino Acid Sequence↗
PubMed1991

Expression of the avirulence gene avrBs3 from Xanthomonas campestris pv. vesicatoria is not under the control of hrp genes and is independent of plant factors.

The avirulence gene avrBs3 from Xanthomonas campestris pv. vesicatoria pepper race 1 is responsible for the induction of a race-specific hypersensitive reaction in resistant pepper cultivars. A DNA region of 3.7 kb, containing several open reading frames and an internal repetitive region, was shown previously to be necessary for avirulence activity (U. Bonas, R. E. Stall, and B. Staskawicz, Mol. Gen. Genet. 218:127-136, 1989). The promoter of avrBs3 was identified by using gene fusions to beta-glucuronidase. Also, we mapped the transcription start site and showed that the avrBs3 gene is expressed constitutively in cells grown in minimal or complex medium and in planta. Polyclonal antibodies raised against a fusion protein produced in Escherichia coli allowed the identification of a 122-kDa protein in X. campestris pv. vesicatoria cells expressing the avrBs3 gene. The antibody is specific for AvrBs3 in X. campestris pv. vesicatoria cells but also recognizes homologous proteins in other pathovars of X. campestris. We found that AvrBs3 is localized intracellularly in X. campestris pv. vesicatoria and is mainly in the soluble fraction. The effect of mutations in the hrp gene cluster on the function of AvrBs3 was examined. Expression of AvrBs3 in X. campestris pv. vesicatoria grown in minimal or complex medium is independent of the hrp gene cluster that determines pathogenicity and hypersensitivity to X. campestris pv. vesicatoria. In the plant, however, the hrp genes are required for elicitation of a race-specific resistance response.

Amino Acid Sequence↗
PubMed1989

Genetic and structural characterization of the avirulence gene avrBs3 from Xanthomonas campestris pv. vesicatoria.

The avirulence gene avrBs3 from Xanthomonas campestris pv. vesicatoria was cloned and found to be localized on a self-transmissable plasmid. Genetic analysis of an avrBs3 insertion mutation revealed that avrBs3 constitutes a single locus, specifying the resistant phenotype on pepper plants. Southern blot experiments showed that no DNA sequences homologous to avrBs3 were present in other races of X. c. pv. vesicatoria, which are unable to induce a hypersensitive reaction on ECW-30R. However, the DNA of several different pathovars of X. campestris hybridized to the avrBs3 probe. A deletion analysis defined a region of 3.6-3.7 kb essential for avrBs3 activity. The nucleotide sequence of this region was determined. A 3561 nucleotide open reading frame (ORF1), encoding a 125,000 dalton protein, was found in the 3.7 kb region that was sufficient for avrBs3 activity. A second long ORF (2351 nucleotides) was identified on the other strand. A remarkable feature of both ORFs is the presence of 17 direct repeats of 102 bp which share 91%-100% homology with each other.

Amino Acid Sequence↗
PubMed1988

Characterization and expression of two avirulence genes cloned from Pseudomonas syringae pv. glycinea.

Two avirulence genes, avrB and avrC, from race 0 of Pseudomonas syringae pv. glycinea, were sequenced and found to encode single protein products of 36 and 39 kilodaltons, respectively. The proteins had neither recognizable signal peptide sequences nor significant stretches of hydrophobic amino acids that might indicate membrane association. Both avrB and avrC had relatively low position 3 and overall G+C contents, which suggests that they may have been recently introduced into P. syringae pv. glycinea. The deduced amino acid sequences of the proteins encoded by avrB and avrC shared 42% identical amino acids. However, when introduced into race 4 of P. syringae pv. glycinea, each gene directed a unique pattern of hypersensitive reactions on several differential soybean cultivars. The avrC protein was overproduced in Escherichia coli cells and deposited as insoluble inclusion bodies in the cell cytoplasm. The avrC protein could be solubilized with urea-octyl glucoside treatment, but neither the solubilized protein nor the intact inclusion bodies elicited a hypersensitive reaction in soybean leaves.

Amino Acid Sequence↗
PubMed1987

Molecular characterization of cloned avirulence genes from race 0 and race 1 of Pseudomonas syringae pv. glycinea.

A wide-host-range cosmid cloning vector, pLAFR3, was constructed and used to make cosmid libraries of partially digested Sau3A DNA from race 0 and race 1 of Pseudomonas syringae pv. glycinea. Two avirulence genes, avrB0 and avrC, cloned from race 0, elicited the hypersensitivity reaction (HR) on specific cultivars of soybean. Race 4 transconjugants containing avrB0 induced a dark brown necrotic HR within 24 h on the soybean cultivars Harosoy and Norchief, whereas race 4 transconjugants containing avrC induced a light brown necrotic HR within 48 h on the soybean cultivars Acme, Peking, Norchief, and Flambeau. An additional avirulence gene, avrB1, cloned from race 1, appeared to be identical to avrB0 from race 0. The avrB0 and avrC genes from race 0 were characterized by restriction enzyme mapping, Southern blot analysis, Tn5 transposon mutagenesis, and site-directed gene replacements. The effects of these three genes on the in planta bacterial growth of race 4 transconjugants have also been examined. The identification and cloning of avrB1 provides genetic evidence for a gene-for-gene interaction in the bacterial blight disease of soybean, as avrB1 from race 1 interacts with the soybean disease resistance locus, Rpg1.

Cloning, Molecular↗
PubMed1987

Molecular characterization and nucleic acid sequence of an avirulence gene from race 6 of Pseudomonas syringae pv. glycinea.

A gene was previously cloned from Pseudomonas syringae pv. glycinea race 6, designated avirulence gene A (avrA), that controls the expression of virulence by the pathogen on specific cultivars of soybean. A 3.2-kilobase (kb) AccI subclone from the cosmid clone pPg6L3 was shown to be active when cloned into the broad-host-range vector pRK404. Transposon Tn5 mutagenesis and deletion analysis delineated a span of approximately 2.5 kb of DNA that was necessary for gene activity. The nucleotide sequence of a 3.409-kb segment of DNA which contained the avrA gene has been determined. An open reading frame of 2.721 kb of DNA, which correlates with the region of DNA defined by transposon mutagenesis and deletion analysis, was identified. The open reading frame would encode a protein of 100.866 kilodaltons, which is in good agreement with the 100-kilodalton protein expressed by Escherichia coli maxicells.

Amino Acid Sequence↗
PubMed1984

Molecular cloning of pectate lyase genes from Erwinia chrysanthemi and their expression in Escherichia coli.

A genomic library of Erwinia chrysanthemi EC16 was constructed in plasmid pHC79, and seven putative pectate lyase (PL) clones in Escherichia coli were selected on pectate agar. Six of the recombinant cosmids contained a common PstI fragment of ca. 8.2 kilobases (kb). Subcloning of this fragment in either orientation into the PstI site of plasmid pBR329 resulted in E. coli transformants that produced a PL of pI 9.8 which was indistinguishable from one of two PLs produced by strain EC16. A 6.6-kilobase PstI fragment from the remaining cosmid clone caused production of an Erwinia PL of pI 8.8 when the fragment was subcloned in either orientation into plasmid pBR329 and transformed into E. coli. Selected pBR329 subclones for the 8.2- and 6.6-kilobase PstI fragments showed no similarity in their restriction maps and did not cross-hybridize. All of the E. coli cosmid clones that produced large amounts of PL also caused soft-rot of potato tubers and tuber slices, thus confirming the role of the enzymes in plant tissue maceration. The E. coli cosmid clones and plasmid pBR329 subclones produced the PLs constitutively, unlike Erwinia chrysanthemi, which made the enzymes inducibly. However, catabolite repression appeared to function in the E. coli clones, and almost all of the PL activity occurred in the periplasm and culture fluids. Thus, the Erwinia PL clones appear to contain signal peptide sequences, transcription and translation signals, and a recognition sequence for the catabolite activator protein, all of which function efficiently in E. coli.

Base Sequence↗