TY - JOUR
T1 - Structural insights into loss of function of a pore forming toxin and its role in pneumococcal adaptation to an intracellular lifestyle
AU - Badgujar, Dilip C.
AU - Anil, Anjali
AU - Green, Angharad E.
AU - Surve, Manalee Vishnu
AU - Madhavan, Shilpa
AU - Beckett, Alison
AU - Prior, Ian A.
AU - Godsora, Barsa K.
AU - Patil, Sanket B.
AU - More, Prachi Kadam
AU - Sarkar, Shruti Guha
AU - Mitchell, Andrea
AU - Banerjee, Rinti
AU - Phale, Prashant S.
AU - Mitchell, Timothy J.
AU - Neill, Daniel R.
AU - Bhaumik, Prasenjit
AU - Banerjee, Anirban
N1 - Funding Information:
DRN and AEG acknowledge funding from a Wellcome Trust and Royal Society Sir Henry Dale Fellowship awarded to DRN (Grant No. 204457/Z/ 16/Z). PB acknowledges financial support from Ramalingaswami Re-entry Fellowship (Dept. of Biotechnology, Govt. of India, Grant No. BT/RLF/ Re-entry/42/2011) and research grant from Dept. of Science & Technology, Govt. of India (Grant No. EMR/2016/006067). AB acknowledges research funding from Council of Scientific & Industrial Research, Govt. of India (Grant No. 27/0331/18/ EMR-II) and Science and Engineering Research Board, Govt. of India (Grant No. EMR/2016/ 005909). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Publisher Copyright:
Copyright: © 2020 Badgujar et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PY - 2020/11/20
Y1 - 2020/11/20
N2 - The opportunistic pathogen Streptococcus pneumoniae has dual lifestyles: one of an asymptomatic colonizer in the human nasopharynx and the other of a deadly pathogen invading sterile host compartments. The latter triggers an overwhelming inflammatory response, partly driven via pore forming activity of the cholesterol dependent cytolysin (CDC), pneumolysin. Although pneumolysin-induced inflammation drives person-to-person transmission from nasopharynx, the primary reservoir for pneumococcus, it also contributes to high mortality rates, creating a bottleneck that hampers widespread bacterial dissemination, thus acting as a double-edged sword. Serotype 1 ST306, a widespread pneumococcal clone, harbours a non-hemolytic variant of pneumolysin (Ply-NH). Performing crystal structure analysis of Ply-NH, we identified Y150H and T172I as key substitutions responsible for loss of its pore forming activity. We uncovered a novel inter-molecular cation-π interaction, governing formation of the transmembrane β-hairpins (TMH) in the pore state of Ply, which can be extended to other CDCs. H150 in Ply-NH disrupts this interaction, while I172 provides structural rigidity to domain-3, through hydrophobic interactions, inhibiting TMH formation. Loss of pore forming activity enabled improved cellular invasion and autophagy evasion, promoting an atypical intracellular lifestyle for pneumococcus, a finding that was corroborated in in vivo infection models. Attenuation of inflammatory responses and tissue damage promoted tolerance of Ply-NH-expressing pneumococcus in the lower respiratory tract. Adoption of this altered lifestyle may be necessary for ST306 due to its limited nasopharyngeal carriage, with Ply-NH, aided partly by loss of its pore forming ability, facilitating a benign association of SPN in an alternative, intracellular host niche.
AB - The opportunistic pathogen Streptococcus pneumoniae has dual lifestyles: one of an asymptomatic colonizer in the human nasopharynx and the other of a deadly pathogen invading sterile host compartments. The latter triggers an overwhelming inflammatory response, partly driven via pore forming activity of the cholesterol dependent cytolysin (CDC), pneumolysin. Although pneumolysin-induced inflammation drives person-to-person transmission from nasopharynx, the primary reservoir for pneumococcus, it also contributes to high mortality rates, creating a bottleneck that hampers widespread bacterial dissemination, thus acting as a double-edged sword. Serotype 1 ST306, a widespread pneumococcal clone, harbours a non-hemolytic variant of pneumolysin (Ply-NH). Performing crystal structure analysis of Ply-NH, we identified Y150H and T172I as key substitutions responsible for loss of its pore forming activity. We uncovered a novel inter-molecular cation-π interaction, governing formation of the transmembrane β-hairpins (TMH) in the pore state of Ply, which can be extended to other CDCs. H150 in Ply-NH disrupts this interaction, while I172 provides structural rigidity to domain-3, through hydrophobic interactions, inhibiting TMH formation. Loss of pore forming activity enabled improved cellular invasion and autophagy evasion, promoting an atypical intracellular lifestyle for pneumococcus, a finding that was corroborated in in vivo infection models. Attenuation of inflammatory responses and tissue damage promoted tolerance of Ply-NH-expressing pneumococcus in the lower respiratory tract. Adoption of this altered lifestyle may be necessary for ST306 due to its limited nasopharyngeal carriage, with Ply-NH, aided partly by loss of its pore forming ability, facilitating a benign association of SPN in an alternative, intracellular host niche.
UR - http://www.scopus.com/inward/record.url?scp=85097139432&partnerID=8YFLogxK
U2 - 10.1371/journal.ppat.1009016
DO - 10.1371/journal.ppat.1009016
M3 - Article
C2 - PMC7717573
SN - 1553-7366
VL - 16
JO - PLoS Pathogens
JF - PLoS Pathogens
IS - 11
M1 - e1009016
ER -