Functional characterization of murB-potABCD operon for polyamine uptake and peptidoglycan synthesis in Streptococcus suis

Abstract

Spermidine (Spd), spermine (Spm), and putrescine (Put), which are the most widely distributed cellular polyamines, are essential for normal growth and multiplication of both eukaryotic and prokaryotic cells. In this study, we identified the only putative polyamine transport system PotABCD in Streptococcus suis, a worldwide zoonotic Gram-positive pathogen causing lethal infections in humans and pigs. It was discovered that S. suis could uptake polyamines preferably Spd and Spm. By constructing a potA deleted mutant, we confirmed that PotABCD was responsible for polyamine uptake, and PotD bound to the protein of polyamines. The four PotABCD genes were co-transcribed with murB, a gene involved in peptidoglycan (PG) synthesis. Furthermore the roles of polyamine transport system in maintaining the PG structure were detected to understand the biological significance of this co-transcription. In contrast to the wild type, the mutant ΔpotA exhibited elongated chain length and abnormal cell division morphology. Phenotypic changes were attributed to be the up-regulation of genes involved in PG synthesis and hydrolysis in ΔpotA. Additionally, polyamines functioned not only as feedback regulators of PotA by inhibiting PotA activity but also as regulators on potABCD and genes involved in PG synthesis. This study reveals the functions of PotABCD in polyamine transport and the regulatory roles of polyamines in PG synthesis. Results provide new insights into the machineries contributing to normal growth and cell division of S. suis.

12/111phiA Prophage Domestication Is Associated with Autoaggregation and Increased Ability to Produce Biofilm in Streptococcus agalactiae

“…Remarkably, the four plasmid-complemented mutants displayed stronger autoaggregation than that observed with 12/111, along with frequent cell heterogeneity and abnormal septation. In S. suis, long chains with abnormal septation have been associated with unstable peptidoglycan due to the deletion of potA, a major part of the potABCD polyamine transporter [ 80 ]. SAM is a key determinant of the synthesis of AI-2 and of polyamines [ 64 , 65 ], i.e., molecules which play a role in peptidoglycan synthesis in Streptococci [ 80 , 81 ] and in biofilm formation [ 82 , 83 ].…”

“…In S. suis, long chains with abnormal septation have been associated with unstable peptidoglycan due to the deletion of potA, a major part of the potABCD polyamine transporter [ 80 ]. SAM is a key determinant of the synthesis of AI-2 and of polyamines [ 64 , 65 ], i.e., molecules which play a role in peptidoglycan synthesis in Streptococci [ 80 , 81 ] and in biofilm formation [ 82 , 83 ]. Thus, we suggest that (1) the stronger autoaggregation and higher cell heterogeneity with abnormal septation observed in our study with the plasmid-complemented strains may have resulted from increased synthesis of AI-2 and polyamines due to the overexpression of metK carried on the plasmids, and (2) metK may play a role in quorum sensing and peptidoglycan synthesis.…”

Peptidylarginine Deiminase Inhibitors Reduce Bacterial Membrane Vesicle Release and Sensitize Bacteria to Antibiotic Treatment

“…A recent review has demonstrated the presence of different types of vesicles released from both Gram-negative and Gram-positive bacteria, indicating also that the composition of the cell membrane plays a role in vesiculation (Toyofuku et al, 2019). The presence of a thickened peptidoglycan cell wall in Gram-positive bacteria restricts the penetration of most drugs into the cells, which suggests the need of an alternative receptor-mediated transport system (Liu et al, 2018). However, the high lipid content of the Gram-negative cell membrane with a thin layer of peptidoglycan increases membrane fluidity thus facilitating OMV release (Roier et al, 2016).…”

Polyamine Function in Plants: Metabolism, Regulation on Development, and Roles in Abiotic Stress Responses

“…Polyamines are ubiquitous in eukaryotic and prokaryotic cells (Liu et al, 2016, 2017), and are found even in plant RNA viruses and plant tumors. They have potent biological activities.…”

“…Polyamines (PAs) are low molecular weight aliphatic nitrogenous bases containing two or more amino groups, and they have potent biological activity (Xu et al, 2009; Vuosku et al, 2018). They are widely distributed in eukaryotic and prokaryotic cells (Liu et al, 2017; Mustafavi et al, 2018). In living organisms, PAs mainly exist in free (F-PAs), covalently conjugated (CC-PAs) or non-covalently conjugated (NCC-PAs) forms (Gholami et al, 2013).…”