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Quaternary Structure of the Tryptophan Synthase ?-Subunit Homolog BX1 from Zea mays.

ABSTRACT: BX1 from Zea mays (zmBX1) is an enzyme of plant secondary metabolism that generates indole for the synthesis of plant defensins. It is a homologue of the tryptophan synthase ?-subunit, TrpA. Whereas TrpA itself is a monomer in solution, zmBX1 is dimeric, confirmed in our work by native MS. Using cross-linking and mutagenesis, we identified the physiological dimerization interface of zmBX1. We found that homodimerization has only minor effects on catalysis and stability. A comparison of the zmBX1-zmBX1 homodimer and zmTrpA-zmTrpB heterodimer interfaces suggest that homodimerization in zmBX1 might, at an early point in evolution, have served as a mechanism to exclude the interaction with the tryptophan synthase ?-subunit (zmTrpB), marking its transition from primary to secondary metabolism.

SUBMITTER: Norris A

PROVIDER: S-EPMC7313238 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Quaternary Structure of the Tryptophan Synthase α-Subunit Homolog BX1 from <i>Zea mays</i>.

Norris Andrew A Busch Florian F Schupfner Michael M Sterner Reinhard R Wysocki Vicki H VH

Journal of the American Society for Mass Spectrometry 20200113 2

BX1 from <i>Zea mays</i> (zmBX1) is an enzyme of plant secondary metabolism that generates indole for the synthesis of plant defensins. It is a homologue of the tryptophan synthase α-subunit, TrpA. Whereas TrpA itself is a monomer in solution, zmBX1 is dimeric, confirmed in our work by native MS. Using cross-linking and mutagenesis, we identified the physiological dimerization interface of zmBX1. We found that homodimerization has only minor effects on catalysis and stability. A comparison of th ...[more]

PMID: 31933363

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Characterisation of the tryptophan synthase alpha subunit in maize.

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