Analysis of the mutant proBA operon from a proline-producing strain of Serratia marcescens

Abstract

The nucleotide sequence of the proBA operon from a proline-hyperproducing mutant of Serratia marcescens was determined. Two base substitutions were found: one in theproBstructura1 gene, coding for y-glutamyl kinase (GK), and a second one in the promoter region of the operon. The former base substitution led to a change of the predicted amino acid at position 117 from an alanine to a valine in GK. This mutation rendered GK 700-fold less sensitive to proline-mediated feedback inhibition than the wild-type enzyme. The other base substitution, a transversion from a G-C to an A-T, was located in the spacer region between the ' -35' and ' -10' sequences of the promoter, and it increased the transcriptional activity of this operon fourfold. Both these two base substitutions, which were acquired at the step of selecting mutants resistant to a toxic proline analogue, 3,4-dehydroproline, confer upon cells a high proline productivity and an increased osmotolerance.

Gene Dosage Effect of l -Proline Biosynthetic Enzymes on l -Proline Accumulation and Freeze Tolerance in Saccharomyces cerevisiae

“…Position 154 in ␥-GK may be important for the formation of the ␥-GK-␥-GPR complex, and the replacement of Asp154 by Asn may facilitate an intermolecular interaction that stabilizes the complex. This mutation at position 154 in the S. cerevisiae ␥-GK is novel in that different mutations in other amino acid residues required for feedback inhibition of ␥-GK by L-proline were identified in bacterial and plant genes that have been studied (5,6,13,21,35). Based on the prediction of the secondary structure by the method of Chou and Fasman (3), Asp154 in the yeast ␥-GK protein is believed to be located in a turn-like region between an ␣-helix (Val147-Phe152) and a ␤-sheet (Thr157-Thr182), which is probably on the molecular surface.…”

Differential expression of two P5CS genes controlling proline accumulation during salt‐stress requires ABA and is regulated by ABA1, ABI1 and AXR2 in Arabidopsis

“…Accordingly, amino acid residues involved in proline inhibition of bacterial γ-GK enzymes (Csonka study indicated that two P5CS genes are also present in alfalfa (Zilberstein and Szabados, unpublished). Diveret al, 1988;Omori et al, 1992) were not found to be conserved in the Vigna P5CS sequence (Hu et al, 1992).…”

“…In contrast, the newly identified AtP5CS2 1991, Csonka et al, 1988;Omori et al, 1992) were not found to be conserved in the Arabidopsis P5CS sequences, gene is active in dividing cells, as well as transcribed in other plant tissues albeit at lower levels than AtP5CS1. In which also lacked typical signal peptides for potential chloroplast transport.…”

Characterization of mutations induced by N-methyl-N′-nitro-N-nitrosoguanidine in an industrial Corynebacterium glutamicum strain

“…However, as far as we know, there has been no report examining the mutagenic specificities of NTG on a genome-wide scale in classically derived industrial production strains. Brevibacterium flavum and Brevibacterium lactofermentum [10][11][12][13][14][15][16], Escherichia coli [17], and Serratia marcescens [18]. Results are summarized in Table 1, which includes two cases of the NTG-induced mutations.…”