Developmental biology ofStreptomycesfrom the perspective of 100 actinobacterial genome sequences

Abstract

To illuminate the evolution and mechanisms of actinobacterial complexity, we evaluate the distribution and origins of known Streptomyces developmental genes and the developmental significance of actinobacteria-specific genes. As an aid, we developed the Actinoblast database of reciprocal blastp best hits between the Streptomyces coelicolor genome and more than 100 other actinobacterial genomes (http://streptomyces.org.uk/actinoblast/). We suggest that the emergence of morphological complexity was underpinned by special features of early actinobacteria, such as polar growth and the coupled participation of regulatory Wbl proteins and the redox-protecting thiol mycothiol in transducing a transient nitric oxide signal generated during physiologically stressful growth transitions. It seems that some cell growth and division proteins of early actinobacteria have acquired greater importance for sporulation of complex actinobacteria than for mycelial growth, in which septa are infrequent and not associated with complete cell separation. The acquisition of extracellular proteins with structural roles, a highly regulated extracellular protease cascade, and additional regulatory genes allowed early actinobacterial stationary phase processes to be redeployed in the emergence of aerial hyphae from mycelial mats and in the formation of spore chains. These extracellular proteins may have contributed to speciation. Simpler members of morphologically diverse clades have lost some developmental genes.

Plant growth promotion by streptomycetes: ecophysiology, mechanisms and applications

“…Although morphological characteristics are typically important for Streptomyces identification, some studies have demonstrated that classification based on cell morphology, colony pigmentation, and physiological features do not always reflect the natural phylogenetic relationship between actinobacteria and related organisms [21]. Introduction of the polyphasic taxonomic approach combined molecular and biochemical analyses which elucidated streptomycetes systematics.…”

“…Introduction of the polyphasic taxonomic approach combined molecular and biochemical analyses which elucidated streptomycetes systematics. In addition, increased availability of 16S rRNA sequence data has enabled accurate studies of taxonomic affiliations and phylogenetic relationships [15,21,22].…”

Cyclic Dinucleotide-Controlled Regulatory Pathways in Streptomyces Species

“…3). Moreover, translation of the PDE RmdB in S. coelicolor also seems to depend on BldA due to the presence of a TTA codon in rmdB (54). The regulation of several c-di-GMP metabolizing enzymes by the developmental regulators BldD, WhiA, and BldA further emphasizes the central role of c-di-GMP signaling in Streptomyces differentiation.…”

“…Orthologs of bldD show high conservation and local synteny and are found in all sporulating actinomycetes (54). Moreover, the c-di-GMP binding signature is present in all sequenced bldD orthologs and c-di-GMP is predicted to be present in all sporulating actinomycetes.…”

“…bldD is an ancient gene that was present in very early actinobacteria but that has been lost several times in the course of evolution of the phylum (54). Orthologs of bldD show high conservation and local synteny and are found in all sporulating actinomycetes (54).…”