We want to learn how Gram-positive bacteria control their synthesis of secondary metabolites -- substances that they produce only after vegetative growth and cell division have stopped. Such products include antibiotics, toxins, a number of enzymes, and a variety of small molecules. We will use as a model system the production of acetoin (2-oxo, 3-hydroxy-butane) by Bacillus subtilis. This compound is excreted by stationary-phase cells in large quantities. It comes from the decarboxylation of acetolactate, which the bacteria products by means of an enzyme, acetolactate synthase (AlsS), that is synthesized only after growth has stopped. We have cloned and sequenced the alsS gene that encodes AlsS, and an adjacent gene orfX that is transcribed and translated as a divergent operon. AlsA has sequence homology with IlvB, a biosynthetic enzyme of B. subtilis required for the synthesis of branched-chain amino acids. OrfX has sequence homology with a family of positive regulatory proteins found in other bacteria. We want to learn how the alsS gene's expression is controlled so that its product is not detectable during vegetative growth, but is produced once growth stops. We suspect that the orfX gene is involved in this control, but do not have direct evidence for this. A mutation, alsAl, unlinked to alsS, prevents the expression of alsS under all conditions. We have cloned alsA and will determine the role it plays in controlling the expression of alsS.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM043979-01
Application #
3303125
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1990-04-01
Project End
1993-03-31
Budget Start
1990-04-01
Budget End
1991-03-31
Support Year
1
Fiscal Year
1990
Total Cost
Indirect Cost
Name
Cornell University
Department
Type
Schools of Arts and Sciences
DUNS #
City
Ithaca
State
NY
Country
United States
Zip Code
14850
Grandoni, J A; Zahler, S A; Calvo, J M (1992) Transcriptional regulation of the ilv-leu operon of Bacillus subtilis. J Bacteriol 174:3212-9