Polyclonal-Based ELISA for the Identification of Cyclohexanedione Analogs that Inhibit Maize Acetyl Coenzyme-A Carboxylase

Abstract Cyclohexanedione herbicides inhibit monocotyledonous acetyl coenzyme-A carboxylase (ACCase; E.C. 6.4.1.2.), which catalyzes the first committed step in fatty acid biosynthesis. Although the target site has been identified, little is known about the mechanisms involved in herbicide binding. An immunological study was undertaken to create a model to better characterize the herbicide–enzyme interaction. Cyclohexanedione-specific antiserum was raised in New Zealand white rabbits by immunizing them with a cyclohexanedione analog–bovine serum albumin conjugate. Two indirect enzyme-linked immunosorbent assays (ELISA) were developed using 2 different cyclohexanedione analogs conjugated to ovalbumin as coating conjugates. Nineteen cyclohexanedione analogs, 13 active ACCase inhibitors, and 6 inactive analogs were tested for their ability to compete with both coating conjugates for antiserum binding. All active ACCase inhibitors were observed to compete with both coating conjugates, whereas all inactive analogs failed to compete with at least one coating conjugate. On the basis of these results, the immunological model could be used to distinguish all active ACCase inhibitors from inactive analogs using the 2 ELISAs sequentially.

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Inhibition of Acetyl Coenzyme A Carboxylase Activity Restores Expression of the INO1 Gene in a snf1Mutant Strain of Saccharomyces cerevisiae

Molecular and Cellular Biology ◽

10.1128/mcb.21.17.5710-5722.2001 ◽

2001 ◽

Vol 21 (17) ◽

pp. 5710-5722 ◽

Cited By ~ 75

Author(s):

Margaret K. Shirra ◽

Jana Patton-Vogt ◽

Andreas Ulrich ◽

Oksana Liuta-Tehlivets ◽

Sepp D. Kohlwein ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Fatty Acid ◽

Fatty Acid Biosynthesis ◽

Coenzyme A ◽

Phospholipid Biosynthesis ◽

Acid Biosynthesis ◽

Acetyl Coenzyme A ◽

Acetyl Coenzyme ◽

Soraphen A ◽

Acetyl Coenzyme A Carboxylase

ABSTRACT Mutations in the Saccharomyces cerevisiae SNF1 gene affect a number of cellular processes, including the expression of genes involved in carbon source utilization and phospholipid biosynthesis. To identify targets of the Snf1 kinase that modulate expression of INO1, a gene required for an early, rate-limiting step in phospholipid biosynthesis, we performed a genetic selection for suppressors of the inositol auxotrophy ofsnf1Δ strains. We identified mutations inACC1 and FAS1, two genes important for fatty acid biosynthesis in yeast; ACC1 encodes acetyl coenzyme A carboxylase (Acc1), and FAS1 encodes the β subunit of fatty acid synthase. Acc1 was shown previously to be phosphorylated and inactivated by Snf1. Here we show thatsnf1Δ strains with increased Acc1 activity exhibit decreased INO1 transcription. Strains carrying theACC1 suppressor mutation have reduced Acc1 activity in vitro and in vivo, as revealed by enzymatic assays and increased sensitivity to the Acc1-specific inhibitor soraphen A. Moreover, a reduction in Acc1 activity, caused by addition of soraphen A, provision of exogenous fatty acid, or conditional expression ofACC1, suppresses the inositol auxotrophy ofsnf1Δ strains. Together, these findings indicate that the inositol auxotrophy of snf1Δ strains arises in part from elevated Acc1 activity and that a reduction in this activity restores INO1 expression in these strains. These results reveal a Snf1-dependent connection between fatty acid production and phospholipid biosynthesis, identify Acc1 as a Snf1 target important forINO1 transcription, and suggest models in which metabolites that are generated or utilized during fatty acid biosynthesis can significantly influence gene expression in yeast.

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