Function and Redundancy of the Chaplin Cell Surface Proteins in Aerial Hypha Formation, Rodlet Assembly, and Viability in Streptomyces coelicolor
| Autor: | Mark J. Buttner, Marie A. Elliot, Kim Findlay, Christina Di Berardo, David S. Capstick, Maureen J. Bibb |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Hypha
Cell division Molecular Sequence Data Hyphae Germ tube Genetics and Molecular Biology Streptomyces coelicolor Microbiology Bacterial Proteins Amino Acid Sequence Cysteine Molecular Biology Mycelium Microbial Viability Sequence Homology Amino Acid biology Streptomycetaceae Genetic Complementation Test fungi food and beverages Membrane Proteins biology.organism_classification Spore Biochemistry Microscopy Electron Scanning Mutagenesis Site-Directed Ultrastructure |
| Zdroj: | Journal of Bacteriology. 190:5879-5889 |
| ISSN: | 1098-5530 0021-9193 |
| Popis: | The chaplins are a family of eight secreted proteins that are critical for raising aerial hyphae in Streptomyces coelicolor. These eight chaplins can be separated into two main groups: the long chaplins (ChpA to -C) and the short chaplins (ChpD to -H). The short chaplins can be further subdivided on the basis of their abilities to form intramolecular disulfide bonds: ChpD, -F, -G, and -H contain two Cys residues, while ChpE has none. A “minimal chaplin strain” containing only chpC, chpE, and chpH was constructed and was found to raise a substantial aerial mycelium. This strain was used to examine the roles of specific chaplins. Within this strain, the Cys-containing ChpH was identified as the major polymerization unit contributing to aerial hypha formation and assembly of an intricate rodlet ultrastructure on the aerial surfaces, and the two Cys residues were determined to be critical for its function. ChpC augmented aerial hypha formation and rodlet assembly, likely by anchoring the short chaplins to the cell surface, while ChpE was essential for the viability of wild-type S. coelicolor. Interestingly, the lethal effects of a chpE null mutation could be suppressed by the loss of the other chaplins, the inactivation of the twin arginine translocation (Tat) secretion pathway, or the loss of the rodlins. The gram-positive soil-dwelling streptomycetes have a mycelial growth habit that culminates in the formation of dormant exospores that permit survival under adverse environmental conditions (13). Germinating spores produce one or more germ tubes that grow by tip extension to form a network of branching vegetative hyphae known as the vegetative mycelium. Antibiotics (and other secondary metabolites) are produced within the vegetative hyphae, and from this vegetative mycelial network emerge specialized reproductive structures known as aerial hyphae. These aerial hyphae undergo a number of maturation steps, including a synchronous round of cell division, to differentiate into chains of unigenomic spores. The transition from vegetative growth in an aqueous environment to the emergence of aerial hyphae into the air requires significant adaptation of the cell surface: the surfaces of vegetative hyphae are hydrophilic, while those of aerial hyphae and spores are extremely hydrophobic. Three groups of proteins are known to be involved in the modulation of cell surfaces during aerial hypha formation in Streptomyces coelicolor: the chaplins, the rodlins, and SapB (reviewed in references 8, 16, and 36). These proteins are thought to collectively function like the fungal hydrophobins, which are important for surface modulation and aerial growth in the filamentous fungi (reviewed in reference 37). Hydrophobins are small secreted proteins that assemble |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|