In Silico Analysis and Functional Characterization of Fhub, a Component of Erwinia Mallotivora Ferric Hydroxamate Uptake System

Abstract

Iron is a critical element for bacterial growth as most pathogenic bacteria relies on their host for iron supply. However, iron sources are bounded to the host iron binding protein and specific iron acquisition mechanism is required to chelate and transport the iron to the bacteria. Ferric hydroxamate uptake system or fhu is one of the transport systems that import iron in the form of ferric hydroxamate/ ferrichrome from the extracellular environment into the bacterial cytosol. In this present study, a detailed in silico structural analysis was conducted on an important component of fhu transport member from Erwinia mallotivora named as fhuB. This provide us the structural properties of the protein which includes the domain and 3D model, phylogenetic analysis and the membrane topology. For functional analysis, a knockout mutant of fhuB gene strain was generated to evaluate the effect of silencing this gene during E. mallotivora infection in papaya. When compared to the wild E. mallotivora strain, fhuB mutant strain of E. mallotivora loss its virulence in causing dieback disease symptom in papaya. The result of this study has revealed the significant role of iron acquisition and metabolism during E. mallotivora pathogenesis. This highlights fhuB role and importance as the target gene; to inhibit iron uptake in E. mallotivora for future study and as a part of future consideration for dieback disease management strategy in papaya.

Characterisation and Mutagenesis Study of An Alternative Sigma Factor Gene (hrpL) from Erwinia mallotivora Reveal Its Central Role in Papaya Dieback Disease

“…To investigate the involvement of hrpL in E. mallotivora pathogenicity, the Δ Em hrpL strain was used to artificially inoculate four-month-old papaya plants and the resulting disease severity was compared against severity produced by wild type E. mallotivora (positive control). The progression of dieback disease severity (averaged) on papaya plants caused by Δ Em hrpL vs. wild type strain is shown in Table 4 and it was based on the 0–5 papaya dieback disease severity score [ 21 ]. Upon infection with the Δ Em hrpL strain, the papaya plants manifested zero symptoms during 3–12 DPI.…”

“…Disease severity was scored following the study conducted by Juri et al [ 21 ]. Disease severity scoring was evaluated using a 5-stage scale as follows: 0—symptomless; 1—leaf vein blackening; 2—leaf vein blackening + slight wilting; 3—leaf stalk wilting; 4—stem blackening; 5—plant death.…”

Genome Sequencing and Analysis of Trichoderma (Hypocreaceae) Isolates Exhibiting Antagonistic Activity against the Papaya Dieback Pathogen, Erwinia mallotivora

“…About four years after the identification of the pathogen, the draft genome sequence of E. mallotivora was published and this has initiated more research [ 4 ]. Wee et al [ 14 ], Hamid et al [ 15 ], Juri et al [ 16 , 17 ], Abu-Bakar et al [ 18 ], Abu Bakar et al [ 19 ], and Tamizi et al [ 20 ] have conducted in-depth studies to understand the host–pathogen interactions and pathogenicity of E. mallotivora at the molecular level, while Noor Shahida et al [ 6 ] described the infection from a physiological perspective. The use of conventional breeding and genetic engineering to develop new papaya lines that would be resistant to E. mallotivora is still in the research pipelines [ 21 , 22 , 23 , 24 , 25 ].…”