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Calmodulin‐mediated suppression of 2‐ketoisovalerate reductase in Beauveria bassiana beauvericin biosynthetic pathway
Author(s) -
Kim Jiyoung,
Yoon DeokHyo,
Oh Junsang,
Hyun MinWoo,
Han JaeGu,
Sung GiHo
Publication year - 2016
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.13461
Subject(s) - beauvericin , beauveria bassiana , biology , bassiana , biochemistry , enzyme , reductase , proline , microbiology and biotechnology , mycotoxin , amino acid , botany , biological pest control
Summary Ketoisovalerate reductase (KIVR, E.C. 1.2.7.7) mediates the specific reduction of 2‐ketoisovalerate (2‐Kiv) to d ‐hydroxyisovalerate ( d ‐Hiv), a precursor for beauvericin biosynthesis. Beauvericin, a famous mycotoxin produced by many fungi, is a cyclooligomer depsipeptide, which has insecticidal, antimicrobial, antiviral, and cytotoxic activities. In this report, we demonstrated that Beauveria bassiana 2‐ketoisovalerate reductase (BbKIVR) acts as a typical KIVR enzyme in the entomopathogenic fungus B. bassiana . In addition, we found that BbKIVR interacts with calmodulin (CaM) in vitro and in vivo . The functional role of CaM‐binding to BbKIVR was to negatively regulate the BbKIVR activity in B. bassiana . Environmental stimuli such as light and salt stress suppressed BbKIVR activity in B. bassiana . Interestingly, this negative effect of BbKIVR activity by light and salt stress was recovered by CaM inhibitors, suggesting that the inhibitory mechanism is mediated through stimulation of CaM activity. Therefore, this work suggests that BbKIVR plays an important role in the beauvericin biosynthetic pathway mediated by environmental stimuli such as light and salt stress via the CaM signaling pathway.