Two genes encoding proteins with similarities to rubredoxin and rubredoxin reductase are required for conversion of dodecane to lauric acid in Acinetobacter calcoaceticus ADP1

Abstract

Mutants of Acinetobacter calcoaceticus ADP1 unable to grow on dodecane, but retaining the ability to grow on lauric acid were isolated after ethylmethanesulphonate (EMS) treatment. This growth deficiency was complemented by a clone from a gene library constructed from chromosomal DNA of the wild-type strain. The complementing DNA mapped in a gene encoding a polypeptide with homology to rubredoxins. The deduced putative rubredoxin amino acid sequence is more similar to related proteins from Gram-positive bacteria than to the Pseudomonas oleovorans rubredoxin involved in alkane oxidation. An adjacent gene encodes a protein with similarity to rubredoxin reductase from Pseudomonas oleovorans and related NAD(P)-dependent reductases. Disruption of the rubredoxin-encoding gene by insertion of a KmR/lacZ cassette rendered the resulting strain unable to grow on dodecane or hexadecane. This demonstrates that these genes are necessary for alkane degradation. Transcriptional fusion of lacZ to the rubredoxin-encoding gene led to low level constitutive beta-galactosidase expression, whereas the fusion oriented in the opposite direction was not expressed.

Identification of Electrode Respiring, Hydrocarbonoclastic Bacterial Strain Stenotrophomonas maltophilia MK2 Highlights the Untapped Potential for Environmental Bioremediation

“…Such a fusion would be responsible for the extended spectrum of alkane degradation up to C36 hydrocarbons shown in the present study, as alk B often reported to be responsible for <C16 length (van Beilen and Funhoff, 2007). Also, the earlier studies on the disruption of the rub A encoding genes in bacterial strains lead to the failure of alkane degradation (Haspel et al, 1995; Ratajczak et al, 1998) which supports the aforementioned theory on fused proteins in hydrocarbon biodegradation.…”

Bioengineering for the Microbial Degradation of Petroleum Hydrocarbon Contaminants

“…Gene alkM is different from alkB in DNA sequence homology. However, AlkM is still recognized to belong to integral-membrane alkane hydroxylases for it also needs rubredoxin and rubredoxin reductase [ 53 ]. The gene of AlkM also differs from AlkB in its positional relationship with the gene of coenzyme.…”