Streptomyces genes involved in aerial mycelium formation

Horinouchi, S

doi:10.1016/0378-1097(96)00170-x

Cited by 15 publications

(19 citation statements)

References 20 publications

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“…In the gram-positive, filamentous bacterium Streptomyces griseus, A-factor (2-isocapryloyl-3R-hydroxymethyl-␥-butyrolactone) acts as a chemical signaling molecule, or microbial hormone, that triggers secondary metabolism and cellular differentiation at an extremely low concentration (7)(8)(9). It serves as a switch for biosynthesis of streptomycin and almost all secondary metabolites and for formation of aerial mycelium.…”

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Transcriptional Switch On of ssgA by A-Factor, Which Is Essential for Spore Septum Formation in Streptomyces griseus

2003

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A-factor (2-isocapryloyl-3R-hydroxymethyl-␥-butyrolactone) triggers morphological development and secondary metabolism in Streptomyces griseus. A transcriptional activator (AdpA) in the A-factor regulatory cascade switches on a number of genes required for both processes. AdBS11 was identified in a library of the DNA fragments that are bound by AdpA and mapped upstream of ssgA, which is essential for septum formation in aerial hyphae. Gel mobility shift assays and DNase I footprinting revealed three AdpA-binding sites at nucleotide positions about ؊235 (site 1), ؊110 (site 2), and ؉60 (site 3) with respect to the transcriptional start point, p1, of ssgA. ssgA had two transcriptional start points, one starting at 124 nucleotides (p1) and the other starting at 79 nucleotides (p2) upstream of the start codon of ssgA. Of the three binding sites, only sites 1 and 2 were required for transcriptional activation of p1 and p2 by AdpA. The transcriptional switch on of ssgA required the extracytoplasmic function sigma factor, AdsA , in addition to AdpA. However, it was unlikely that AdsA recognized the two ssgA promoters, since their ؊35 and ؊10 sequences were not similar to the promoter sequence motifs recognized by BldN , a AdsA homologue of Streptomyces coelicolor A3(2). An ssgA disruptant formed aerial hyphae, but did not form spores, irrespective of the carbon source of the medium, which indicated that ssgA is a member of the whi genes. Transcriptional analysis of ssfR, located just upstream of ssgA and encoding an IclR-type transcriptional regulator, suggested that no read-through from ssfR into ssgA occurred, and ssgA was transcribed in the absence of ssfR. ssgA was thus found to be controlled by AdpA and not by SsfR to a detectable extent. SsfR appeared to regulate spore septum formation independently of SsgA or through interaction with SsgA in some unknown way, because an ssfR disruptant also showed a whi phenotype.

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Transcriptional Switch On of ssgA by A-Factor, Which Is Essential for Spore Septum Formation in Streptomyces griseus

2003

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“…In Streptomyces griseus, A-factor (2-isocapryloyl-3R-hydroxymethyl-␥-butyrolactone) at an extremely low concentration acts as a switch for aerial mycelium formation and secondary metabolite formation (9)(10)(11). An A-factor-deficient S. griseus mutant strain neither forms aerial mycelium nor produces streptomycin.…”

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Control by A-Factor of a Metalloendopeptidase Gene Involved in Aerial Mycelium Formation in Streptomyces griseus

et al. 2002

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In Streptomyces griseus, A-factor (2-isocapryloyl-3R-hydroxymethyl-␥-butyrolactone) switches on aerial mycelium formation and secondary metabolite biosynthesis. An A-factor-dependent transcriptional activator, AdpA, activates multiple genes required for morphological development and secondary metabolism in a programmed manner. A region upstream of a zinc-containing metalloendopeptidase gene (sgmA) was found among the DNA fragments that had been isolated as AdpA-binding sites. The primary product of sgmA consisted of N-terminal pre, N-terminal pro, mature, and C-terminal pro regions. sgmA was transcribed in an AdpA-dependent manner, and its transcription was markedly enhanced at the timing of aerial mycelium formation. AdpA bound two sites in the region upstream of the sgmA promoter; one was at about nucleotide position ؊60 (A site) with respect to the transcriptional start point of sgmA, and the other was at about position ؊260 (B site), as determined by DNase I footprinting. Transcriptional analysis with mutated promoters showed that the A site was essential for the switching on of sgmA transcription and that the B site was necessary for the marked enhancement of transcription at the timing of aerial mycelium formation. Disruption of the chromosomal sgmA gene resulted in a delay in aerial hypha formation by half a day. SgmA is therefore suggested to be associated with the programmed morphological development of Streptomyces, in which this peptidase, perhaps together with other hydrolytic enzymes, plays a role in the degradation of proteins in substrate hyphae for reuse in aerial hypha formation.Members of the gram-positive, soil-inhabiting, filamentous bacterial genus Streptomyces produce a wide variety of secondary metabolites and show complex morphological differentiation culminating in sporulation. These characteristics make members of this genus important as industrial microorganisms and as one of the model prokaryotes for studying multicellular differentiation (3, 4). On agar medium, one or more germ tubes formed from a germinating spore grow into substrate hyphae, which branch frequently and grow rapidly by cell wall extension at the hyphal tips. Subsequently, aerial hyphae emerge by reuse of material assimilated into the substrate mycelium, such as DNA, proteins, and storage compounds. Many cells in substrate hyphae thus lyse and die (5,21,31). At this stage of development, therefore, enzymes for the degradation of these substances, such as proteases, nucleases, lipases, and glucanases, are presumably required. In fact, nucleases and serine proteases are associated with the development of aerial hyphae from substrate hyphae (5, 23). When the apical growth of aerial hyphae stops, in contrast to the substrate mycelium, septa are formed at regular intervals along the hyphae to form many unigenomic compartments within a sheath. The sporulation septa consist of two membrane layers separated by a double layer of cell wall material, which permits the eventual separation of adjacent spores (7). Spore chains usua...

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“…For example, Streptomyces coelicolor A3(2) bld mutants are defective in both aerial mycelium formation and antibiotic production, depending on the carbon source of medium (9). A-factor (2-isocapryloyl-3R-hydroxymethyl-␥-butyrolactone) is another example that acts as a switch for aerial mycelium formation and secondary metabolite formation in Streptomyces griseus (18)(19)(20). Downstream from the common regulatory pathway, there must be a regulatory pathway specific to morphological differentiation and secondary metabolism.…”

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An A-Factor-Dependent Extracytoplasmic Function Sigma Factor (ς ^AdsA ) That Is Essential for Morphological Development in Streptomyces griseus

2000

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AdsA. Transcription of adsA depended on A-factor and AdpA, since adsA was transcribed at a very low and constant level in an A-factor-deficient mutant strain or in an adpA-disrupted strain. Consistent with this, transcription of adsA was greatly enhanced at or near the timing of aerial hyphae formation, as determined by low-resolution S1 nuclease mapping. High-resolution S1 mapping determined the transcriptional start point 82 nucleotides upstream of the translational start codon. DNase I footprinting showed that AdpA bound both strands symmetrically between the transcriptional start point and the translational start codon; AdpA protected the antisense strand from positions ؉7 to ؉41 with respect to the transcriptional start point and the sense strand from positions ؉12 to ؉46. A weak palindrome was found in the AdpA-binding site. The unusual position bound by AdpA as a transcriptional activator, in relation to the promoter, suggested the presence of a mechanism by which AdpA activates transcription of adsA in some unknown way. Disruption of the chromosomal adsA gene resulted in loss of aerial hyphae formation but not streptomycin or yellow pigment production, indicating that AdsA is involved only in morphological development and not in secondary metabolic function. The presence of a single copy in each of the Streptomyces species examined by Southern hybridization suggests a common role in morphogenesis in this genus.

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Streptomyces genes involved in aerial mycelium formation

Cited by 15 publications

References 20 publications

Transcriptional Switch On of ssgA by A-Factor, Which Is Essential for Spore Septum Formation in Streptomyces griseus

Transcriptional Switch On of ssgA by A-Factor, Which Is Essential for Spore Septum Formation in Streptomyces griseus

Control by A-Factor of a Metalloendopeptidase Gene Involved in Aerial Mycelium Formation in Streptomyces griseus

An A-Factor-Dependent Extracytoplasmic Function Sigma Factor (ς ^AdsA ) That Is Essential for Morphological Development in Streptomyces griseus

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Streptomyces genes involved in aerial mycelium formation

Cited by 15 publications

References 20 publications

Transcriptional Switch On of ssgA by A-Factor, Which Is Essential for Spore Septum Formation in Streptomyces griseus

Transcriptional Switch On of ssgA by A-Factor, Which Is Essential for Spore Septum Formation in Streptomyces griseus

Control by A-Factor of a Metalloendopeptidase Gene Involved in Aerial Mycelium Formation in Streptomyces griseus

An A-Factor-Dependent Extracytoplasmic Function Sigma Factor (ς AdsA ) That Is Essential for Morphological Development in Streptomyces griseus

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An A-Factor-Dependent Extracytoplasmic Function Sigma Factor (ς ^AdsA ) That Is Essential for Morphological Development in Streptomyces griseus