Coordinated regulation of anthranilate metabolism and bacterial virulence by the GntR family regulator MpaR in Pseudomonas aeruginosa.

The GntR family regulators are widely distributed in bacteria and play critical roles in metabolic processes and bacterial pathogenicity. In this study, we describe a GntR family protein encoded by PA4132 that we named MpaR (MvfR-mediated PQS and anthranilate regulator) for its regulation of Pseudomonas quinolone signal (PQS) production and anthranilate metabolism in Pseudomonas aeruginosa. The deletion of mpaR increased biofilm formation and reduced pyocyanin production. RNA sequencing analysis revealed that the mRNA levels of antABC encoding enzymes for the synthesis of catechol from anthranilate, a precursor of the PQS, were most affected by mpaR deletion. Data showed that MpaR directly activates the expression of mvfR, a master regulator of pqs system, and subsequently promotes PQS production. Accordingly, deletion of mpaR activates the expression of antABC genes, and thus, increases catechol production. We also demonstrated that MpaR represses the rhl quorum-sensing (QS) system, which has been shown to control antABC activity. These results suggested that MpaR function is integrated into the QS regulatory network. Moreover, mutation of mpaR promotes bacterial survival in a mouse model of acute pneumonia infection. Collectively, this study identified a novel regulator of pqs system, which coordinately controls anthranilate metabolism and bacterial virulence in P. aeruginosa.

High throughput screening of semiconductors with low lattice thermal transport induced by long-range interactions.

Semiconductors with long-range interactions (LRI) due to resonant bonding exhibit delocalized electronic states and low lattice thermal conductivity, contributing to the efficiency of heat-to-electricity conversion. Here, we build a descriptor for high-throughput screening of LRI materials from the second-order interaction force constants. We identify 75 semiconducting candidates from the binary compounds in the MatHub-3d database that contain LRI. By analyzing the bonding properties of LRI atoms, we classify LRI in materials into two categories: type I and type II. In the structural unit of type I LRI, the atoms have strong bond connections, while a weak bond exists between the two groups in the structural unit of type II LRI. We have identified atypical type I LRI formed by Sb-Sb and Mg-Mg pairs in the emerging thermoelectric material Mg3Sb2, resulting in the softening of TA1 phonons and large anharmonicity. For type II LRI, the LRI of Ge-Ge and Se-Se pairs in R3m-GeSe can cross different layers. Moreover, we observe a combination of type II LRI and rattling effect in BaSe2 to restrict thermal transport. This work is of great significance for understanding the relationship between LRI and thermal transport properties, and for designing new LRI-induced low lattice thermal conductivity materials.

Pseudomonas aeruginosa T6SS-mediated molybdate transport contributes to bacterial competition during anaerobiosis.

Type VI secretion system (T6SS) is widely distributed in Gram-negative bacteria and functions as a versatile protein export machinery that translocates effectors into eukaryotic or prokaryotic target cells. Growing evidence indicates that T6SS can deliver several effectors to promote bacterial survival in harmful environments through metal ion acquisition. Here, we report that the Pseudomonas aeruginosa H2-T6SS mediates molybdate (MoO42-) acquisition by secretion of a molybdate-binding protein, ModA. The expression of H2-T6SS genes is activated by the master regulator Anr and anaerobiosis. We also identified a ModA-binding protein, IcmP, an insulin-cleaving metalloproteinase outer membrane protein. The T6SS-ModA-IcmP system provides P. aeruginosa with a growth advantage in bacterial competition under anaerobic conditions and plays an important role in bacterial virulence. Overall, this study clarifies the role of T6SS in secretion of an anion-binding protein, emphasizing the fundamental importance of this bacterium using T6SS-mediated molybdate uptake to adapt to complex environmental conditions.