Role of substrate mycelium in colony development in <i>Streptomyces</i>

Méndez, Cármen; Braña, Alfredo F.; Manzanal, Manuel B.; Hardisson, Carlos

doi:10.1139/m85-083

Cited by 84 publications

(71 citation statements)

References 7 publications

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“…In addition, the onset of aerial mycelium formation coincides with a noticeable lysis of the substrate hyphae (2,3). This fact, together with the absence of an increase in dry weight during the development of the aerial mycelium and the displacement of labeled protein precursors from the substrate to the aerial mycelium (3), supports the hypothesis that the aerial mycelium reuses material first assimilated into the substrate mycelium. These events, which occur in stressful environmental conditions, are directed to generate and disseminate spores that have a greater potential for survival.…”

supporting

confidence: 56%

“…The S. antibioticus chymotrypsin-like protease shows a higher capability to degrade protein substrates than TLP. 3 Our present results suggest that the S. antibioticus TLP is involved in the processing of nuclease precursors rather than just contributing to the general turnover of substrate mycelium proteins, although this additional function cannot be excluded.…”

Section: Discussionmentioning

confidence: 55%

“…No other TLP proteases have been detected in S. antibioticus throughout the developmental cycle, although a serine protease of a chymotrypsin type has also been detected in the culture medium. 3 An enzyme with these characteristics was also detected in S. exfoliatus (35), and it was suggested that it participated in the utilization of external proteinaceous nitrogen sources. The S. antibioticus chymotrypsin-like protease shows a higher capability to degrade protein substrates than TLP.…”

Section: Discussionmentioning

confidence: 98%

“…Activity Gel Analysis-Plates of solid GAE medium (3) were used to analyze the production of the different exocellular nuclease forms of S. antibioticus ATCC11891. The nucleases were directly extruded from the medium by forcing the agar through the nozzle (about 2 mm across) of a 20-ml plastic syringe (Becton Dickinson) without needle.…”

Section: Methodsmentioning

confidence: 99%

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Purification, Characterization, and Role of Nucleases and Serine Proteases in Streptomyces Differentiation

Nicieza

Huergo

Connolly

et al. 1999

Journal of Biological Chemistry

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Two exocellular nucleases with molecular masses of 18 and 34 kDa, which are nutritionally regulated and reach their maximum activity during aerial mycelium formation and sporulation, have been detected in Streptomyces antibioticus. Their function appears to be DNA degradation in the substrate mycelium, and in agreement with this proposed role the two nucleases cooperate efficiently with a periplasmic nuclease previously described in Streptomyces antibioticus to completely hydrolyze DNA. The nucleases cut DNA nonspecifically, leaving 5-phosphate mononucleotides as the predominant products. Both proteins require Mg 2؉ , and the additional presence of Ca 2؉ notably stimulates their activities. The two nucleases are inhibited by Zn 2؉ and aurin tricarboxylic acid. The 18-kDa nuclease from Streptomyces is reminiscent of NUC-18, a thymocyte nuclease proposed to have a key role in glucocorticoid-stimulated apoptosis. The 18-kDa nuclease was shown, by aminoterminal protein sequencing, to be a member of the cyclophilin family and also to possess peptidylprolyl cistrans-isomerase activity. NUC-18 has also been shown to be a cyclophilin, and "native" cyclophilins are capable of DNA degradation. The S. antibioticus 18-kDa nuclease is produced by a proteolytic processing from a less active protein precursor. The protease responsible has been identified as a serine protease that is inhibited by N ␣ -ptosyl-L-lysine chloromethyl ketone and leupeptin. Inhibition of both of the nucleases or the protease impairs aerial mycelium development in S. antibioticus. The biochemical features of cellular DNA degradation during Streptomyces development show significant analogies with the late steps of apoptosis of eukaryotic cells.The actinomycetes are a large group of filamentous bacteria that are adapted for growth in soil by forming a ramifying network, called a mycelium. Within this group the predominant isolates belong to the genus Streptomyces, which produce a well developed branched mycelium on agar plates, resulting in a compact colony. In the vegetative phase, the filaments often lack cross-walls (substrate mycelium) and thus have several copies of the chromosome. When the colony ages, a characteristic aerial mycelium is formed, in response to unknown signals involving nutrient limitation, which subsequently fragment and/or sporulate by the synchronous formation of crosswalls in the multinucleate sporophores followed by separation of the individual cells directly into spores. This is similar to the growth and differentiation of fungi, and from the morphological and metabolic points of view, Streptomyces can be considered as boundary organisms (1). Coincident with the morphological differentiation, the streptomycetes produce numerous compounds (secondary metabolites) within which antibiotics are of commercial relevance. As corresponds to their habitat, these bacteria are nutritionally quite versatile, and most produce extracellular hydrolytic enzymes that permit the utilization of polysaccharides, proteins, fats, and other substrat...

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supporting

confidence: 56%

Section: Discussionmentioning

confidence: 55%

Section: Discussionmentioning

confidence: 98%

Section: Methodsmentioning

confidence: 99%

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Purification, Characterization, and Role of Nucleases and Serine Proteases in Streptomyces Differentiation

Nicieza

Huergo

Connolly

et al. 1999

Journal of Biological Chemistry

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“…The cell death paroxysm at the transition phase causes intensive release of intracellular compounds into the extracellular environment (Manteca et al 2006). The latter are thought to serve as nutritive sources for surviving vegetative filaments to grow and differentiate in the aerial structures (Mendez et al 1985). This form of 'altruistic cannibalism' or 'programmed autophagy' is now commonly admitted but almost nothing is known about the assimilation of the cellular compounds released during PCD (lipids, nucleic acids, proteins, phosphorylated sugars, polyphosphate, ions, etc.).…”

Section: Introductionmentioning

confidence: 99%

Extracellular sugar phosphates are assimilated by Streptomyces in a PhoP-dependent manner

Tenconi

Jourdan

Motté

et al. 2012

Antonie van Leeuwenhoek

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Filamentous microorganisms of the bacterial genus Streptomyces have a complex life cycle that includes physiological and morphological differentiations. It is now fairly well accepted that lysis of Streptomyces vegetative mycelium induced by programmed cell death (PCD) provides the required nutritive sources for the bacterium to erect sporeforming aerial hyphae. However, little is known regarding cellular compounds released during PCD and the contribution of these molecules to the feeding of surviving cells in order to allow them to reach the late stages of the developmental program. In this work we assessed the effect of extracellular sugar phosphates (that are likely to be released in the environment upon cell lysis) on the differentiation processes.We demonstrated that the supply of phosphorylated sugars, under inorganic phosphate limitation, delays the occurrence of the second round of PCD, blocks streptomycetes life cycle at the vegetative state and inhibits antibiotic production. The mechanism by which sugar phosphates affect development was shown to involve genes of the Pho regulon that are under the positive control of the two component system PhoR/PhoP. Indeed, the inactivation of the response regulator phoP of Streptomyces lividans prevented the 'sugar phosphate effect' whereas the S. lividans ppk (polyphosphate kinase) deletion mutant, known to overexpress the Pho regulon, presented an enhanced response to phosphorylated sugars.

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Regulation of Bacterial Antibiotic Production

Chater¹,

Bibb²

1997

Biotechnology

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Role of substrate mycelium in colony development in Streptomyces

Cited by 84 publications

References 7 publications

Purification, Characterization, and Role of Nucleases and Serine Proteases in Streptomyces Differentiation

Purification, Characterization, and Role of Nucleases and Serine Proteases in Streptomyces Differentiation

Extracellular sugar phosphates are assimilated by Streptomyces in a PhoP-dependent manner

Regulation of Bacterial Antibiotic Production

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