RESUMO
In bacterial populations, quorum sensing (QS) systems participate in the regulation of specialization processes and regulate collective behaviors that mediate interactions and allow survival of the species. In Gram-positive bacteria, QS systems of the RRNPP family (Rgg, Rap, NprR, PlcR, and PrgX) consist of intracellular receptors and their cognate signaling peptides. Two of these receptors, Rap and NprR, have regained attention in Bacillus subtilis and the Bacillus cereus group. Some Rap proteins, such as RapH and Rap60, are multifunctional and/or redundant in function, linking the specialization processes of sporulation and competence, as well as global expression changes in the transition phase in B. subtilis NprR, an evolutionary intermediate between Rap and RRNPP transcriptional activators, is a bifunctional regulator that modulates sporulation initiation and activates nutrient scavenging genes. In this review, we discuss how these receptors switch between functions and connect distinct signaling pathways. Based on structural evidence, we propose that RapH and Rap60 should be considered moonlighting proteins. Additionally, we analyze an evolutionary and ecological perspective to understand the multifunctionality and functional redundancy of these regulators in both Bacillus spp. and non-Bacillus Firmicutes Understanding the mechanistic, structural, ecological, and evolutionary basis for the multifunctionality and redundancy of these QS systems is a key step for achieving the development of innovative technologies for health and agriculture.
Assuntos
Bacillus/fisiologia , Proteínas de Bactérias/metabolismo , Percepção de Quorum , Bacillus/genética , Bacillus/crescimento & desenvolvimento , Proteínas de Bactérias/genética , Regulação Bacteriana da Expressão Gênica , Esporos Bacterianos/genética , Esporos Bacterianos/crescimento & desenvolvimento , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
This study focuses on the prevalence of Listeria monocytogenes (Lm) in pork meat and on inert surfaces from slaughterhouses in Sonora, Mexico. A total of 21 Lm were obtained from 103 samples, giving a prevalence of 20.3%. The prevalence of Lm in pork loin was 15.9% and 20.8% for inert surfaces in Federal Inspection Type (FIT) slaughterhouses. For non-FIT slaughterhouses, the prevalence was 25.7%. PCR amplification of genomic DNA from the Lm isolates revealed the presence of the hlyA gene, suggesting a pathogenic nature for these isolates. The isolates obtained in this work all clustered with Lm, according to our phylogenetic analysis based on the 16S rDNA sequence. This Lm cluster indicates that Lm isolates 7-2, 4, 2-1, 10B, 8, 3, 3-3, and 9 share 16S rRNA identity with other Lm isolates that have been reported as foodborne pathogens (rR2-502, J1817, J1816, J1926) and that are involved in foodborne outbreaks. The most commonly detected serotypes were 1/2a and 1/2b. All isolates displayed differential responses to the assayed antibiotics, and most isolates were able to grow in the presence of penicillin G, or both penicillin and penicillin-derived (oxacillin) antibiotics.