Reticulitermes flavipes (Kollar) is best known throughout southwestern counties of Ontario, Canada, as an urban pest. Little is known, however, of the presence of this termite in nonurban settings in Ontario. In this study, we confirmed the existence of a population of R. flavipes on the shores of Lake Erie within Point Pelee National Park. A systematic trap survey conducted along the park's semi-vegetated west beach revealed several zones of termite activity. An analysis of trap response at one location indicated an association between termite activity and smaller sized, moderately decayed woody debris. Further, microsatellite DNA analysis suggested the presence of at least three genetically distinct colonies, each likely headed by multiple inbred reproductives. Together these data suggest that termite activity is linked to food quality, and that single colonies are potentially long-lived through multiple generations of inbreeding. Assuming it is derived from a population reported from Point Pelee in 1929, the study population is the oldest known eastern subterranean termite population in Ontario.Résumé-Reticulitermes flavipes (Kollar) est connue dans les comtés Sud-ouest de l'Ontario comme étant un ravageur urbain. Très peu d'information est disponible cependant sur sa présence naturelle dans des environnements non-urbains en Ontario. Dans cette étude, nous rapportons l'existence d'une population de R. flavipes sur les rives du lac Erié dans le parc national Point Pelee. Par un piégeage systématique mené le long de la plage ouest semi-végétale du parc, nous avons révélé plusieurs régions avec de l'activité de termites. Une analyse des résultats de piégeage à un endroit indique une association entre l'activité des termites et des petits débris de bois modérément pourris. De plus, une analyse des microsatellites de l'ADN suggère qu'il y a au moins trois colonies génétiquement distinctes, chacune d'elle fondée par plusieurs événements consanguins. Ensemble, ces données suggèrent que l'activité des termites est associée à la qualité de la nourriture présente, et que les colonies individuelles peuvent potentiellement vivre longtemps par le biais de plusieurs générations consanguines. En supposant que les termites situées à Point Pelee proviennent d'une population documentée dans la région en 1929, elle est la population connue de termite sous-terraine la plus âgée en Ontario.
Summary
Many Listeria species including L. monocytogenes contain the pathway for the biosynthesis of protocatechuate from shikimate and quinate. The qui1 and qui2 operons within these Listeria spp. encode enzymes for this pathway. The diversion of shikimate pathway intermediates in some Listeria species to produce protocatechuate suggests an important biological role for this compound to these organisms. A total of seven ORFs, including quiC2, were identified within qui1 and qui2, however only three proteins encoded by the operons have been functionally annotated. The final step in Listeria's protocatechuate biosynthesis involves the conversion of dehydroshikimate by a dehydroshikimate dehydratase (DSD). In this study, we demonstrate that QuiC2 functions as a DSD in Listeria spp. through biochemical and structural analyses. Moreover, we show that QuiC2 forms a phylogenetic cluster distinct from other functionally annotated DSDs. The individual phylogenetic clusters of DSD are represented by enzymes that produce protocatechuate for distinct biological processes. Similarly, QuiC2 is expected to produce protocatechuate for a novel biological process. We postulate that protocatechuate produced by DSDs found within the QuiC2 phylogenetic cluster provides an ecological niche for representative organisms.
The shikimate pathway is an essential metabolic pathway in bacteria, as well as plants and fungi, which ultimately leads to the synthesis of three aromatic amino acids among other important aromatic compounds. The fourth step in the pathway is the reduction of dehydroshikimate to shikimate, catalyzed by shikimate dehydrogenase (SDH/AroE). In addition to AroE, at least four functionally distinct SDH homologs exist in bacteria. The structure and catalytic residues of the SDH enzyme family are highly conserved, however the key residues for substrate binding vary among the different homologs. Together, these data suggest that the catalytic mechanism is maintained among homologs, yet each may bind a different substrate. The YdiB homolog catalyzes the first step in the quinate degradation pathway, which is a branch of the shikimate pathway. In various species, the operons containing the ydiB gene are predicted to be controlled by one of two different transcriptional regulators belonging to either the TetR or LysR family. In both cases, these regulators are predicted to be activated or repressed by intermediates of the quinate degradation pathway. We will be using structural biology to determine how these regulators recognize pathway intermediates, and to understand the structural basis of how two distinct regulators can control transcription of the equivalent operon in different species.
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