Disease relevance of modA

• The X. citri modA gene was cloned in pET28a and the recombinant protein, expressed in the E. coli BL21 (DE3) strain, purified by immobilized metal affinity chromatography [1].

High impact information on modA

• Among the various oxyanions tested, only tungstate replaced molybdate in the repression of modA by ModE, but the affinity of ModE-tungstate for modABCD operator DNA was 6 times lower than with ModE-molybdate [2].
• Mutants in modA or modBC were unable to grow using nitrate or Mo-nitrogenase [3].
• However, relative to modA, binding of ModE to the moaA promoter appeared to be largely molybdate independent both in vitro and in vivo [4].
• Compared to the full-length protein, the N-terminal half of ModE has a greatly diminished capacity to bind the modA promoter in vitro and to repress expression from a modA-lacZ operon fusion in vivo [5].
• This level was increased by over 175 times by a mutation in the modA, modB, or modC gene [6].

Biological context of modA

• However, by using a plasmid carrying a modA-lacZ gene fusion we observed that inactivation of modR releases repression of the mod operon independent of the molybdate concentration in the medium [7].
• A regulatory motif, CATAA, located at the modA promoter was identified and shown to be required for molybdate-dependent control of the modABCD operon [8].
• A single open reading frame, designated modA, was identified and appears to encode a periplasmic binding protein for the molybdate uptake system [8].

Associations of modA with chemical compounds

• Since the modA product has a signal peptide at the N-terminus it probably is the periplasmic binding-protein for molybdate [7].

Analytical, diagnostic and therapeutic context of modA

• Utilizing an in vivo titration assay, we localized the ModE-binding site to the start of modA transcription [4].

References