Cloning and characterization of a plasmid encoded ACC deaminase from an indigenous Pseudomonas fluorescens FY32.
In addition to the characterized mechanisms responsible for many direct effects of plant growth promoting bacteria (PGPB) on plants, it has been suggested that a number of PGPB contain the enzyme ACC deaminase that catalyzes degradation of 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, into alpha-ketobutyrate and ammonia. As part of an effort to obtain an ACC deaminase encoding gene from a collection of soil samples, only one bacterial isolate, Pseudomonas fluorescens FY32 was capable of growing on ACC as a sole source of nitrogen. The ACC deaminase gene was amplified from the above isolate by polymerase chain reaction (PCR) giving an expected DNA fragment, 1017 bp. Sequence analysis of the fragment showed that it was highly homologous (94% and 98% identities at nucleotide and amino acid levels, respectively) to the previously characterized acdS gene from Pseudomonas sp. 6G5. Furthermore, fusion of the ACC deaminase ORF with lacZ gene resulted in the expression of active enzyme in Escherichia coli. In addition, further analyses revealed that the acdS gene was plasmid-encoded so that a large plasmid (pFY32) with almost 50 kb in size was identified from this bacterium. Furthermore, transfer of pFY32 into E. coli DH5alpha proved its ACC deaminase activity. This result was in accordance with previous reports suggesting horizontal transfer of the acdS gene. However, it needs more investigation to identify whether this pFY32 plasmid has undergone lateral gene transfer during the evolutionary process.
Farajzadeh
Davoud
D
Soil Biology and Biotechnology Department, University of Tabriz, P.O. Box 51664, Tabriz, Iran. farajzadeh@tabrizu.ac.ir
Aliasgharzad
Naser
N
Sokhandan Bashir
Nemat
N
Yakhchali
Bagher
B
D000598:Amino Acids, Cyclic / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D019755:Carbon-Carbon Lyases / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D005030:Ethylenes / Q000378:metabolism; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D010802:Phylogeny; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011551:Pseudomonas fluorescens / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid
D000598:Amino Acids, Cyclic; D000900:Anti-Bacterial Agents; D005030:Ethylenes; D011993:Recombinant Fusion Proteins; C023863:1-aminocyclopropane-1-carboxylic acid; C036216:ethylene; C033634:1-aminocyclopropane-1-carboxylate deaminase; D019755:Carbon-Carbon Lyases