7% identity over the entire sequence of 233 amino acids [37]. Orthologues of SCO3857 are conserved among several streptomycete genomes, including organisms that like S. coelicolor are selleckchem not resistant to thiopeptide antibiotics like nosiheptide and thiostrepton and do not carry a homologue of the nshR resistance gene that is linked to nshA in S. actuosus. This suggests alternative functions for SCO3857 than control of thiopeptide resistance. The SCO3857 gene showed a clear developmental up-regulation in the wild-type parent, and this was dependent on both whiA and whiH (Figure  5). The mCherry reporter

assays showed a high level of expression in sporulating aerial hyphae, but not in vegetative hyphae (Figure  7). Finally,

although a SCO3857 deletion mutant produced normal-looking colonies on MS agar (Figure  8), we detected a reduced heat-resistance of the mutant spores compared to the parent strain (Figure  9). These observations identify SCO3857 as a sporulation gene with a role in maturation of spores. Other developmentally regulated loci The SCO4421 gene encodes a TetR family regulator and is located close to afsK (SCO4423), which encodes a Ser/Thr protein kinase involved in apical growth and branching of hyphae, as well as in control of secondary metabolism [38, 39]. SCO4421 showed statistically significant up-regulation in the parent strain M145 and decreased expression in the whiA mutant in the array data (Figure  2 and find more Additional file 1: Table S1). The developmental regulation was not tested by qRT-PCR, but was confirmed by the mCherry reporter construct that showed clear signal in spore chains but not in vegetative hyphae (Figure  7 and Table  1). We did not detect any phenotype associated with the SCO4421 deletion mutant (Figure  8), and its function during sporulation therefore remains unclear. https://www.selleckchem.com/products/ganetespib-sta-9090.html SCO4157 encodes

a putative trypsin-like serine protease. The developmental up-regulation and the decreased expression in both whiA and whiH mutants was confirmed by S1 nuclease protection assays (Figure  6B). The assays pinpointed a 5′-end for SCO4157 Farnesyltransferase transcripts that overlaps with the predicted translational start, and this signal was strongly increased during development of strain M145, but was much weaker in the whiA mutant. A delayed up-regulation was seen in the whiH strain (Figure  6B). Further, there is contribution from promoters located upstream of the probe used in these assays, possibly from the SCO4158 gene. The mCherry reporter gene assays for SCO4157 showed a low but significant signal in developing spores (Figure  7 and Table  1), further supporting that SCO4157 is expressed during sporulation. The discovery of a protease that is expressed during sporulation is interesting in relation to the known involvement of extracellular proteases and protease inhibitors in controlling development of S. coelicolor and other streptomycetes [3, 40].