Protein secretion pathways in Bacillus subtilis: implication for optimization of heterologous protein secretion.
The absence of an outer membrane in Bacillus subtilis can simplify the protein secretion pathways and allow the organism to secrete high levels of extracellular proteins. Of the three known secretory routes, Sec-SRP pathway can direct the majority of secretory proteins into the growth medium. Alternatively, a small number of exoproteins with specific functions are secreted via Tat pathway or ABC transporters in B. subtilis. The discriminating function of precursor proteins among these pathways is largely attributed to the distinct structure of their cleavable signal peptides. Individual secretion machinery components with their special functions are involved in the total flow of proteins from the cytoplasm to the medium. Notably, multiple regulators with signal transduction functions can affect expression of secretion machinery as well as their post-transcriptional actions for protein secretion, resulting in the complicated networks in B. subtilis. Ultimately, according to the available knowledge of secretion machinery, several approaches aimed at optimizing protein secretion are discussed.
Ling Lin Fu
Key Laboratory of Molecular Animal Nutrition, Ministry of Education, College of Animal Sciences, Zhejiang University (Hua Jia Chi Campus), Hangzhou 310029, China.
Zi Rong Xu
Wei Fen Li
Jiang Bing Shuai
Ping Lu
Chun Xia Hu
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D053858:Metabolic Networks and Pathways; D021381:Protein Transport; D018271:Signal Recognition Particle
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D018271:Signal Recognition Particle