A valuable resource available in the search for new natural products is the diverse microbial life that spans the planet. A large subset of these microorganisms synthesize complex specialized metabolites exhibiting biomedically important activities. A limiting step to the characterization of these compounds is an elucidation of the genetic regulatory mechanisms that oversee their production. Although proteins that control transcription initiation of specialized metabolite gene clusters have been identified, those affecting transcription elongation have not been broadly investigated. In this study, we analysed the phylogenetic distribution of the large, widespread NusG family of transcription elongation proteins and found that it includes a cohesive outgroup of paralogues (herein coined LoaP), which are often positioned adjacent or within gene clusters for specialized metabolites. We established Bacillus amyloliquefaciens LoaP as a paradigm for this protein subgroup and showed that it regulated the transcriptional readthrough of termination sites located within two different antibiotic biosynthesis operons. Both of these antibiotics have been implicated in plant-protective activities, demonstrating that LoaP controls an important regulon of specialized metabolite genes for this microorganism. These data therefore reveal transcription elongation as a point of regulatory control for specialized metabolite pathways and introduce a subgroup of NusG proteins for this purpose.

Patients who have pseudohypoparathyroidism type I associated with Albright hereditary osteodystrophy commonly have a genetic deficiency of the a subunit of the G protein that stimulates adenylyl cyclase (aG3) (ATP pyrophosphate-lyase, EC 4.6.1.1). To discover the molecular mechanism that causes aG5 deficiency in these patients, we examined eight kindreds with one or more members affected with Albright hereditary osteodystrophy or pseudohypoparathyroidism and aG. deficiency. In these families, aG. deficiency and the Albright hereditary osteodystrophy phenotype were transmitted together in a dominant inheritance pattern.Using a cDNA hybridization probe for aG., restriction analysis with several endonucleases showed no abnormalities of restriction fragments or gene dosage. RNA blot and dot blot analysis of total RNA from cultured fibroblasts obtained from the patients revealed ==50% reduced mRNA levels for aGS in affected members of six of the pedigrees but normal levels in affected members of the two other pedigrees, compared to mRNA levels in fibroblasts from unaffected individuals. By contrast, mRNA levels encoding the a subunit of the G protein that inhibits adenylyl cyclase were not altered. Our findings suggest that several molecular mechanisms produce aG. deficiency in patients with pseudohypoparathyroidism type Ia and that major gene rearrangements or deletions are not a common cause for aG5 deficiency in pseudohypoparathyroidism type I.

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