Function
One of 8 partially redundant surface-active proteins required for efficient formation of aerial mycelium; the short chaplins assemble into a hydrophobic, amyloidal fibrillar surface layer that envelopes and protects aerial hyphae and spores, presumably anchored to the long chaplins (PubMed:12832396, PubMed:12832397, PubMed:15228525, PubMed:17462011). Chaplins have an overlapping function with the surface-active SapB peptide; chaplins are essential on minimal medium while on rich medium both chaplins and SapB are required for efficient aerial hyphae formation (PubMed:17462011). Chaplins are also involved in cell attachment to a hydrophobic surface (PubMed:19682261). Forms amyloid fibrils in vitro probably composed of stacked beta-sheets, at low extracellular concentrations individually restores the ability to form aerial hyphae to a chaplin-deficient strain, but does so less well than other short chaplins (PubMed:21526199). A small chaplin extract (ChpD, ChpE, ChpF, ChpG and ChpH) self-assembles into 2 different amyloids; small fibrils at the air-water interface form an amiphipathic membrane that resembles spore-surface structures involved in aerial hyphae formation, and hydrophilic fibrils in solution that resemble the fibers that attach cells to a hydrophobic surface. At the air-water interface the hydrophilic surface is in contact with water (probably equivalent to the peptidoglycan layer), while the hydrophobic face is exposed to the air, making the surface of the aerial hyphae hydrophobic (PubMed:24012833). A minimal chaplin strain capable of forming aerial mycelium/hyphae on minimal medium contains ChpC, ChpE and ChpH. The strain also has restored rodlet formation on the hyphae surface. A second strain with ChpA, ChpD and ChpE makes slightly less robust hyphae. This essential chaplin may coordinate the assembly and/or polymerization of the other chaplins (PubMed:18586935). A small chaplin extract applied to a chaplin-deficient strain restores aerial hyphae formation (PubMed:12832396, PubMed:12832397). The small chaplin extract forms an amyloid-like structure similar to that seen on the surface of cells without rodlets (rdlA-rdlB deletions), and is highly surface active, reducing surface tension from 72 to 26 mJ/m(2), which probably allows escape of hyphae from an aqueous environment into air (PubMed:12832396).