INSTITUTO DE INVESTIGACIONES BIOTECNOLOGICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
INTERBACTERIAL COMPETITION ACTIVITY FOR MESORHIZOBIUM JAPONICUM MAFF303099
LEPEK VC; BASILE LA; ZALGUIZURI A
Congreso; Reunión Conjunta SAIB-SAMIGE 2020 Online; 2020
Sociedad Argentina de Investigación en Bioquímica y Biología Molecular
ABSTRACT. Bacteria have toxins that can be used as weapons to inhibit the proliferation of other competing bacteria. This is called interbacterial competition and has been described in different animal and plant pathogens, which use this tool to compete for the occupation of a particular ecological niche. Some of these toxins are translocated from one bacterium to another via the Type VI Secretion System (T6SS). In the laboratory we have developed a new bio-informatic predictive tool based on co-evolution to identify putative effectors of T3SS, T4SS and T6SS of pathogenic and symbiotic bacteria. M. japonicum MAFF303099 codes for a T6SS. We applied this predictive method searching for T6SS effectors in M. japonicum MAFF303099. Among the list of putative effectors, we found a protein with the typical domains of those toxins described as effectors of T6SS in other bacteria, whose role is to prevent the proliferation of a target bacteria. The gene encoding for this putative toxin is mlr6568. We determined that adjacent to this gene there is a gene encoding for a putative immunity protein (antitoxin), mlr6569. This gene pair is flanking a cluster of genes that encode for another contractile injection system, with similar components to those of T6SS, called eCIS (extracellular contractile injection system). The interbacterial competition activity of M. japonicum MAFF303099 against a strain of Escherichia coli was analyzed by comparing E. coli counts (CFU) after incubation with M. japonicum wild type or T6SS mutant strain. The incubation of E. coli with the M. japonicum mutant strain led to a drastic decrease in E. coli counts, indicating that M. japonicum MAFF303099 has the capacity to perform interbacterial competition and that this capacity is negatively regulated by T6SS. T6SS-dependent interbacterial competition had not so far been described for any rhizobia of the alfa-proteobacteria class.