Pullulanase secretion in Escherichia coli K-12 requires a cytoplasmic protein and a putative polytopic cytoplasmic membrane protein

1992 ◽  
Vol 6 (1) ◽  
pp. 95-105 ◽  
Author(s):  
O. Possot ◽  
C. d'Enfert ◽  
I. Reyss ◽  
A. P. Pugsley
1992 ◽  
Vol 267 (8) ◽  
pp. 5339-5345
Author(s):  
B Traxler ◽  
C Lee ◽  
D Boyd ◽  
J Beckwith

2010 ◽  
Vol 192 (13) ◽  
pp. 3329-3336 ◽  
Author(s):  
S. James L. Cariss ◽  
Chrystala Constantinidou ◽  
Mala D. Patel ◽  
Yuiko Takebayashi ◽  
Jon L. Hobman ◽  
...  

ABSTRACT Colicin E2-tolerant (known as Cet2) Escherichia coli K-12 mutants overproduce an inner membrane protein, CreD, which is believed to cause the Cet2 phenotype. Here, we show that overproduction of CreD in a Cet2 strain results from hyperactivation of the CreBC two-component regulator, but CreD overproduction is not responsible for the Cet2 phenotype. Through microarray analysis and gene knockout and overexpression studies, we show that overexpression of another CreBC-regulated gene, yieJ (also known as cbrC), causes the Cet2 phenotype.


2007 ◽  
Vol 189 (20) ◽  
pp. 7273-7280 ◽  
Author(s):  
Dirk-Jan Scheffers ◽  
Carine Robichon ◽  
Gert Jan Haan ◽  
Tanneke den Blaauwen ◽  
Gregory Koningstein ◽  
...  

ABSTRACT The Escherichia coli cell division protein FtsQ is a central component of the divisome. FtsQ is a bitopic membrane protein with a large C-terminal periplasmic domain. In this work we investigated the role of the transmembrane segment (TMS) that anchors FtsQ in the cytoplasmic membrane. A set of TMS mutants was made and analyzed for the ability to complement an ftsQ mutant. Study of the various steps involved in FtsQ biogenesis revealed that one mutant (L29/32R;V38P) failed to functionally insert into the membrane, whereas another mutant (L29/32R) was correctly assembled and interacted with FtsB and FtsL but failed to localize efficiently to the cell division site. Our results indicate that the FtsQ TMS plays a role in FtsQ localization to the division site.


1992 ◽  
Vol 174 (23) ◽  
pp. 7717-7728 ◽  
Author(s):  
Luz-Maria Guzman ◽  
James J. Barondess ◽  
Jon Beckwith

We have identified a gene involved in bacterial cell division, located immediately upstream of the ftsI gene in the min 2 region of the Escherichia coli chromosome. This gene, which we named ftsL , was detected through characterization of Tn phoA insertions in a plasmid containing this chromosomal region. Tn phoA topological analysis and fractionation of alkaline phosphatase fusion proteins indicated that the ftsL gene product is a 13.6-kDa cytoplasmic membrane protein with a cytoplasmic amino terminus, a single membrane-spanning segment, and a periplasmic carboxy terminus. The ftsL gene is essential for cell growth and division. A null mutation in ftsL resulted in inhibition of cell division, formation of long, nonseptate filaments, ultimate cessation of growth, and lysis. Under certain growth conditions, depletion of FtsL or expression of the largest ftsL-phoA fusion produced a variety of cell morphologies, including Y-shaped bacteria, indicating a possible general weakening of the cell wall. The FtsL protein is estimated to be present at about 20 to 40 copies per cell. The periplasmic domain of the protein displays a sequence with features characteristic of leucine zippers, which are involved in protein dimerization.


2014 ◽  
Vol 5 (5) ◽  
pp. 429-438 ◽  
Author(s):  
Ken-ichi Nishiyama ◽  
Keiko Shimamoto

AbstractA novel factor for membrane protein integration, from the cytoplasmic membrane of Escherichia coli, named MPIase (membrane protein integrase), has recently been identified and characterized. MPIase was revealed to be essential for the membrane integration of a subset of membrane proteins, despite that such integration reactions have been, thus far, thought to occur spontaneously. The structure determination study revealed that MPIase is a novel glycolipid comprising a glycan chain with three N-acetylated amino sugars connected to diacylglycerol through a pyrophosphate linker. As MPIase catalyzes membrane protein integration, we propose that MPIase is a glycolipozyme on the basis of its enzyme-like function. The glycan chain exhibits a molecular chaperone-like function by directly interacting with substrate membrane proteins. Moreover, MPIase also affects the dimer structure of SecYEG, a translocon, thereby significantly stimulating preprotein translocation. The molecular mechanisms of MPIase functions will be outlined.


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