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Biochemistry . 2012 Apr 12; Flores Jimenez RH, Cafiso DS Gram-negative bacteria contain a family of outer membrane transport proteins that function in the uptake of rare nutrients, such as iron and vitamin B12. These proteins are termed TonB-dependent because transport requires an interaction with the inner membrane protein TonB. Go here to see the original: Infectious diarrhea has become a kind of extremely severe enteric infectious which caused by Entero-hemorrhagic Escherichia coli(EHEC)O157:H7 in recent years.EHEC O157:H7 could cause infectious … See the original post here: Infectious diarrhea has become a kind of extremely severe enteric infectious which caused by Entero-hemorrhagic Escherichia coli(EHEC)O157:H7 in recent years.EHEC O157:H7 could cause infectious … Read the original here: J Struct Biol . 2012 Mar 29; Efremov RG, Sazanov LA Outer membrane protein F, a major component of the Escherichia coli outer membrane, was crystallized for the first time in lipidic mesophase of monoolein in novel space groups, P1 and H32. Due to ease of its purification and crystallization OmpF can be used as a benchmark protein for establishing membrane protein crystallization in meso, as a “membrane lyzozyme”. Continue reading here: This paper investigated the outer membrane proteins (OMPs) of E. coli K-12 by proteomic approach, especially functional proteomics. On the … Subject, Escherichia coli K-12, outer membrane protein, Proteomics,. FileType … The rest is here: This paper investigated the outer membrane proteins (OMPs) of E. coli K-12 by proteomic approach, especially functional proteomics. On the … Subject, Escherichia coli K-12, outer membrane protein, Proteomics,. FileType … The rest is here: Nat Struct Mol Biol . 2012 Apr 1; Selkrig J, Mosbahi K, Webb CT, Belousoff MJ, Perry AJ, Wells TJ, Morris F, Leyton DL, Totsika M, Phan MD, Celik N, Kelly M, Oates C, Hartland EL, Robins-Browne RM, Ramarathinam SH, Purcell AW, Schembri MA, Strugnell RA, Henderson IR, Walker D, Lithgow T Bacteria have mechanisms to export proteins for diverse purposes, including colonization of hosts and pathogenesis. A small number of archetypal bacterial secretion machines have been found in several groups of bacteria and mediate a fundamentally distinct secretion process See the article here:
Microb Cell Fact. 2012 Apr 4; 11(1): 42 ABSTRACT: BACKGROUND: Caffeic acid (3,4-dihydroxycinnamic acid) is a natural phenolic compound derived from the plant phenylpropanoid pathway. Caffeic acid and its phenethyl ester (CAPE) have attracted increasing attention for their various pharmaceutical properties and health-promoting effects. Nowadays, large-scale production of drugs or drug precursors via microbial approaches provides a promising alternative to chemical synthesis and extraction from plant sources. RESULTS: We first identified that an Escherichia coli native hydroxylase complex previously characterized as the 4-hydroxyphenylacetate 3-hydroxylase (4HPA3H) was able to convert p-coumaric acid to caffeic acid efficiently. This critical enzymatic step catalyzed in plants by a membrane-associated cytochrome P450 enzyme, p-coumarate 3-hydroxylase (C3H), is difficult to be functionally expressed in prokaryotic systems. Moreover, the performances of two tyrosine ammonia lyases (TALs) from Rhodobacter species were compared after overexpression in E. coli. The results indicated that the TAL from R. capsulatus (Rc) possesses higher activity towards both tyrosine and L-dopa. Based on these findings, we further designed a dual pathway leading from tyrosine to caffeic acid consisting of the enzymes 4HPA3H and RcTAL. This heterologous pathway extended E. coli native tyrosine biosynthesis machinery and was able to produce caffeic acid (12.1 mg/L) in minimal salt medium. Further improvement in production was accomplished by boosting tyrosine biosynthesis in E. coli, which involved the alleviation of tyrosine-induced feedback inhibition and carbon flux redirection. Finally, the titer of caffeic acid reached 50.2 mg/L in shake flasks after 48-hour cultivation. CONCLUSION: We have successfully established a novel pathway and constructed an E. coli strain for the production of caffeic acid. This work forms a basis for further improvement in production, as well as opens the possibility of microbial synthesis of more complex plant secondary metabolites derived from caffeic acid. In addition, we have identified that TAL is the rate-limiting enzyme in this pathway. Thus, exploration for more active TALs via bio-prospecting and protein engineering approaches is necessary for further improvement of caffeic acid production. Read the original post:
Microb Cell Fact. 2012 Apr 4; 11(1): 42 ABSTRACT: BACKGROUND: Caffeic acid (3,4-dihydroxycinnamic acid) is a natural phenolic compound derived from the plant phenylpropanoid pathway. Caffeic acid and its phenethyl ester (CAPE) have attracted increasing attention for their various pharmaceutical properties and health-promoting effects. Nowadays, large-scale production of drugs or drug precursors via microbial approaches provides a promising alternative to chemical synthesis and extraction from plant sources. RESULTS: We first identified that an Escherichia coli native hydroxylase complex previously characterized as the 4-hydroxyphenylacetate 3-hydroxylase (4HPA3H) was able to convert p-coumaric acid to caffeic acid efficiently. This critical enzymatic step catalyzed in plants by a membrane-associated cytochrome P450 enzyme, p-coumarate 3-hydroxylase (C3H), is difficult to be functionally expressed in prokaryotic systems. Moreover, the performances of two tyrosine ammonia lyases (TALs) from Rhodobacter species were compared after overexpression in E. coli. The results indicated that the TAL from R. capsulatus (Rc) possesses higher activity towards both tyrosine and L-dopa. Based on these findings, we further designed a dual pathway leading from tyrosine to caffeic acid consisting of the enzymes 4HPA3H and RcTAL. This heterologous pathway extended E. coli native tyrosine biosynthesis machinery and was able to produce caffeic acid (12.1 mg/L) in minimal salt medium. Further improvement in production was accomplished by boosting tyrosine biosynthesis in E. coli, which involved the alleviation of tyrosine-induced feedback inhibition and carbon flux redirection. Finally, the titer of caffeic acid reached 50.2 mg/L in shake flasks after 48-hour cultivation. CONCLUSION: We have successfully established a novel pathway and constructed an E. coli strain for the production of caffeic acid. This work forms a basis for further improvement in production, as well as opens the possibility of microbial synthesis of more complex plant secondary metabolites derived from caffeic acid. In addition, we have identified that TAL is the rate-limiting enzyme in this pathway. Thus, exploration for more active TALs via bio-prospecting and protein engineering approaches is necessary for further improvement of caffeic acid production. Here is the original post: The Bacillus subtilis cannibalism toxin SDP collapses the proton motive force and induces autolysis.Mol Microbiol . 2012 Apr 2; Lamsa A, Liu WT, Dorrestein PC, Pogliano K Bacillus subtilis SDP is a peptide toxin that kills cells outside the biofilm to support continued growth. We show that purified SDP acts like endogenously produced SDP; it delays sporulation, and the SdpI immunity protein confers SDP resistance Continue reading here: GadC glutamate-GABA antiporter: Escherichia coli, 3.10 A Go to Source: GadC glutamate-GABA antiporter: Escherichia coli, 3.10 A Go to Source: |
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