Disease relevance of hrpB

• The ability of Ralstonia solanacearum strain GMI1000 to cause disease on a wide range of host plants (including most Solanaceae and Arabidopsis thaliana) depends on genes activated by the regulatory gene hrpB [1].
• An hrpXv mutant could be partially complemented by the related hrpB gene of Burkholderia solanacearum, the protein product of which shows 40 and 58% amino acid identity and similarity, respectively, to HrpXv [2].

High impact information on hrpB

• This contact-dependent induction of hrpB gene expression requires the outer membrane protein PrhA, but not a functional type III secretion apparatus [3].
• We also identified two novel hrpB-regulated genes, hpaZ and hpaB, downstream of hrpY in the hrp cluster [4].
• In order to isolate type III-related pathogenicity genes, we screened hrpB-regulated genes in R. solanacearum [4].
• Using a transposon-based system, we isolated 30 novel hpx (hrpB-dependent expression) genes outside the hrp gene cluster [4].
• Expression of the popABC operon is controlled by the hrpB regulatory gene and is induced upon co-culture with Arabidopsis cell suspensions [5].

Biological context of hrpB

• As for HrpG of X. c. pv. vesicatoria, HrpG is required for hrp gene expression in minimal medium, but, in addition, we show that it also controls hrpB gene activation upon co-culture with Arabidopsis thaliana and tomato cell suspensions [6].
• Here, we show phenotypes of R. solanacearum mutant strains disrupted in the prhJ, hrpG, or hrpB regulatory genes with respect to root infection and vascular colonization in tomato plants [7].
• A 12,165-bp portion of nucleotide sequence from the presumed left end and extending through the hrpB operon was determined [8].

Other interactions of hrpB

• This indicates that bacterial multiplication at root infection sites and transit through the endodermis constitute critical stages in the infection process, in which hrpB and hrpG genes are involved [7].

References