One of the two genes encoding nucleoid-associated HU proteins in Streptomyces coelicolor is developmentally regulated and specifically involved in spore maturation.
Publikation/Tidskrift/Serie: Journal of bacteriology
Förlag: American Society for Microbiology
Streptomyces genomes encode two homologs of the nucleoid-associated HU-proteins. One of them, here designated HupA, is of a conventional type similar to E. coli HUalpha and HUbeta, while the other, HupS, is a two-domain protein. In addition to the N-terminal part that is similar to HU proteins, it has an additional C-terminal domain that is similar to the alanine and lysine-rich C-termini of eukaryotic linker histones. Such two-domain HU proteins are only found among Actinobacteria. In this phylum some organisms have only a single HU-protein of this type with a C-terminal histone H1-like domain (e. g. Hlp in Mycobacterium smegmatis), while others have only a single conventional HU. Yet others, including the streptomycetes, produce both types of HU-proteins. We show here that the two HU-genes in Streptomyces coelicolor are differentially regulated and that hupS is specifically expressed during sporulation, while hupA is expressed in vegetative hyphae. The developmental upregulation of hupS occurred in sporogenic aerial hyphal compartments, and was dependent on the developmental regulators whiA, whiG, and whiI. HupS was found to be nucleoid-associated in spores, and a hupS deletion mutant had larger average nucleoid size in spores compared to the parent strain. The mutant spores were also defective in heat resistance and spore pigmentation, although they showed apparently normal spore walls and displayed no increased sensitivity to detergents. Overall, the results show that HupS is specifically involved in sporulation and may affect nucleoid architecture and protection in spores of S. coelicolor.
- ISSN: 1098-5530