Modulation of Frankia alni ACN14a oxidative stress response: activity, expression and phylogeny of catalases

• Type: Article in International Scientific Journal
• Date: 2007

Authors

Catarina L Santos (Author) Other; Joao Vieira (Author) Other; Anita Sellstedt (Author) Other; Philippe Normand (Author) Other; Pedro Moradas Ferreira (Author) ICBAS; Fernando Tavares (Author) FCUP

Journal

Title: Physiologia Plantarum

Vol. 130

Pages: 454-463

ISSN: 0031-9317

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 6 Citations

Scopus - 7 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-004-97S

DOI: 10.1111/j.1399-3054.2007.00868.x

Abstract (EN): The finding that an oxidative burst was a general phenomenon in the response of hosts challenged by various symbiotic or pathogenic microbes has stimulated increasing interest in investigating the enzymology of antioxidant protection in bacteria. The question of whether the antioxidant mechanisms have been a decisive evolutionary driving force for the nitrogen-fixing microsymbiont Frankia spp. is still open. In this study, Frankia alni strain ACN14a, which is a mid-range infective strain, was used as a model to explore the basal oxidative stress response in terms of enzymatic activity, relative expression and phylogeny. Non-denaturing polyacrylamide gels stained for catalatic activity revealed the presence of two monofunctional catalases KatA and KatB (EC number 1.11.1.6), which activity was shown to increase when the cells were challenged with the oxidants H2O2 and methyl viologen. Real-time RT-PCR targeting the two genes showed a consistent increase in the number of transcripts when the RNA was extracted from oxidative stress-induced cells. Comparison between the expression and the activity data suggests that posttranscriptional mechanisms might be involved in the regulation of catalases in F. alni. Furthermore, upstream of katA, a fur gene coding for a ferric uptake regulator was found, forming a gene pair that functionally resembles the conserved actinobacterial synton fur-katG, which contains a gene coding for a catalase-peroxidase. Phylogenetic analysis of the F. alni fur-katA synton suggests that this genomic organization was the result of genome reshuffling events.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 10