Protein Family Models

Threonine leader peptide of the Threonine operon thrA1A2BC. It as been sequenced in different bacteria: E. coli, Serratia marcescens, Salmonella typhi [1,2]. [1]. 8423151. Nucleotide sequence of the Serratia marcescens threonine operon and analysis of the threonine operon mutations which alter feedback inhibition of both aspartokinase I and homoserine dehydrogenase I. Omori K, Imai Y, Suzuki S, Komatsubara S;. J Bacteriol 1993;175:785-794. [2]. 12644504. Comparative genomics of Salmonella enterica serovar Typhi strains Ty2 and CT18. Deng W, Liou SR, Plunkett G 3rd, Mayhew GF, Rose DJ, Burland V, Kodoyianni V, Schwartz DC, Blattner FR;. J Bacteriol 2003;185:2330-2337. (from Pfam)

Date:

2024-10-16

This family consists of examples of the threonine biosynthesis (thr) operon leader peptide, also called the thr operon attenuator. The small gene for this peptide is often missed in genome annotation. It should be looked for in genomes of the proteobacteria, immediately upstream of genes for threonine biosynthesis, typically aspartokinase I/homoserine dehydrogenase, homoserine kinase, and threonine synthase. Transcription of the rest of the Thr operon is attenuated (mostly turned off) unless the ribosome pauses during a stretch of the leader sequence rich in both Ile (made from Thr) and in Thr itself because of the scarcity of those amino acids at the time. The leader peptide itself, once made, may have no role other than to be degraded. Similar systems exist for some other amino acid biosynthetic operons, such as Trp.

Gene:

thrL

Date:

2024-05-30

Involved in threonine biosynthesis; controls the expression of the thrLABC operon

Gene:

thrL

Date:

2020-10-26