Christoffels VM

References (2)

Title : A gene of Acinetobacter calcoaceticus BD413 encodes a periplasmic peptidyl-prolyl cis-trans isomerase of the cyclophilin sub-class that is not essential for growth - Kok_1994_Biochim.Biophys.Acta_1219_601
Author(s) : Kok RG , Christoffels VM , Vosman B , Hellingwerf KJ
Ref : Biochimica & Biophysica Acta , 1219 :601 , 1994
Abstract : Downstream of the Acinetobacter calcoaceticus estA gene, encoding a cell-bound esterase, an open reading frame (orf) was identified, which may encode a protein with a mass of 20.4 kDa. This protein shows extensive similarity to both prokaryotic and eukaryotic peptidyl-prolyl cis-trans isomerases (PPIases) of the cyclophilin sub-class, especially to the periplasmic rotamase (RotA) of Escherichia coli. A putative signal sequence suggests that the product of the Acinetobacter gene, we termed rotA, is located outside the cytoplasm. Transcription of the gene is initiated from a promoter, just upstream of the rotA orf. The observation that two A. calcoaceticus rotA deletion mutants display no apparent mutant phenotype, suggests that this PPIase is not essential for growth of the organism. These mutants, to our knowledge, are the first prokaryotic PPIase mutants reported.
ESTHER : Kok_1994_Biochim.Biophys.Acta_1219_601
PubMedSearch : Kok_1994_Biochim.Biophys.Acta_1219_601
PubMedID: 7948017
Gene_locus related to this paper: acica-este2

Title : Growth-phase-dependent expression of the lipolytic system of Acinetobacter calcoaceticus BD413: cloning of a gene encoding one of the esterases - Kok_1993_J.Gen.Microbiol_139_2329
Author(s) : Kok RG , Christoffels VM , Vosman B , Hellingwerf KJ
Ref : J Gen Microbiol , 139 :2329 , 1993
Abstract : Acinetobacter calcoaceticus BD413, when grown in batch culture in nutrient broth, produces both extracellular lipase activity and cell-bound esterase activity during and after the transition between exponential growth and the stationary phase. From a library of A. calcoaceticus DNA in Escherichia coli, plasmids were isolated that enabled E. coli to grow on media with tributyrin as the sole carbon source. Assays with model substrates classified the product of the cloned gene as an esterase. Via deletion analysis, the esterase gene was mapped on a 1.8 kbp chromosomal DNA fragment. This fragment was sequenced and found to contain one open reading frame, termed estA, which encodes a protein of 40.0 kDa. The amino acid sequence of this protein shows homology to a number of lipolytic enzymes, most notably to esterases. Deletion of estA only partially abolished cell-bound esterase activity in A. calcoaceticus, indicating that BD413 forms at least two esterases. Both esterases show the same temporal regulation of expression. beta-Galactosidase activity was measured in strains in which a promoterless lacZ gene was inserted into estA. Induction of lacZ expression in these strains also occurred at the end of exponential growth in batch cultures, indicating that production of the esterase is regulated at the genetic level.
ESTHER : Kok_1993_J.Gen.Microbiol_139_2329
PubMedSearch : Kok_1993_J.Gen.Microbiol_139_2329
PubMedID: 8254303
Gene_locus related to this paper: acica-este1 , acica-este2