Rickettsia typhi possesses phospholipase A2 enzymes that are involved in infection of host cells.

The long-standing proposal that phospholipase A2 (PLA2) enzymes are involved in rickettsial infection of host cells has been given support by the recent characterization of a patatin phospholipase (Pat2) with PLA2 activity from the pathogens Rickettsia prowazekii and R. typhi. However, pat2 is not e...

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Autores principales:	M Sayeedur Rahman, Joseph J Gillespie, Simran Jeet Kaur, Khandra T Sears, Shane M Ceraul, Magda Beier-Sexton, Abdu F Azad
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2013
Materias:	Immunologic diseases. Allergy RC581-607 Biology (General) QH301-705.5
Acceso en línea:	https://doaj.org/article/a9dec9b022fd4010afd1f888fee6c68a
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spelling	oai:doaj.org-article:a9dec9b022fd4010afd1f888fee6c68a2021-11-18T06:05:31ZRickettsia typhi possesses phospholipase A2 enzymes that are involved in infection of host cells.1553-73661553-737410.1371/journal.ppat.1003399https://doaj.org/article/a9dec9b022fd4010afd1f888fee6c68a2013-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/23818842/?tool=EBIhttps://doaj.org/toc/1553-7366https://doaj.org/toc/1553-7374The long-standing proposal that phospholipase A2 (PLA2) enzymes are involved in rickettsial infection of host cells has been given support by the recent characterization of a patatin phospholipase (Pat2) with PLA2 activity from the pathogens Rickettsia prowazekii and R. typhi. However, pat2 is not encoded in all Rickettsia genomes; yet another uncharacterized patatin (Pat1) is indeed ubiquitous. Here, evolutionary analysis of both patatins across 46 Rickettsia genomes revealed 1) pat1 and pat2 loci are syntenic across all genomes, 2) both Pat1 and Pat2 do not contain predicted Sec-dependent signal sequences, 3) pat2 has been pseudogenized multiple times in rickettsial evolution, and 4) ubiquitous pat1 forms two divergent groups (pat1A and pat1B) with strong evidence for recombination between pat1B and plasmid-encoded homologs. In light of these findings, we extended the characterization of R. typhi Pat1 and Pat2 proteins and determined their role in the infection process. As previously demonstrated for Pat2, we determined that 1) Pat1 is expressed and secreted into the host cytoplasm during R. typhi infection, 2) expression of recombinant Pat1 is cytotoxic to yeast cells, 3) recombinant Pat1 possesses PLA2 activity that requires a host cofactor, and 4) both Pat1 cytotoxicity and PLA2 activity were reduced by PLA2 inhibitors and abolished by site-directed mutagenesis of catalytic Ser/Asp residues. To ascertain the role of Pat1 and Pat2 in R. typhi infection, antibodies to both proteins were used to pretreat rickettsiae. Subsequent invasion and plaque assays both indicated a significant decrease in R. typhi infection compared to that by pre-immune IgG. Furthermore, antibody-pretreatment of R. typhi blocked/delayed phagosomal escapes. Together, these data suggest both enzymes are involved early in the infection process. Collectively, our study suggests that R. typhi utilizes two evolutionary divergent patatin phospholipases to support its intracellular life cycle, a mechanism distinguishing it from other rickettsial species.M Sayeedur RahmanJoseph J GillespieSimran Jeet KaurKhandra T SearsShane M CeraulMagda Beier-SextonAbdu F AzadPublic Library of Science (PLoS)articleImmunologic diseases. AllergyRC581-607Biology (General)QH301-705.5ENPLoS Pathogens, Vol 9, Iss 6, p e1003399 (2013)
institution	DOAJ
collection	DOAJ
language	EN
topic	Immunologic diseases. Allergy RC581-607 Biology (General) QH301-705.5
spellingShingle	Immunologic diseases. Allergy RC581-607 Biology (General) QH301-705.5 M Sayeedur Rahman Joseph J Gillespie Simran Jeet Kaur Khandra T Sears Shane M Ceraul Magda Beier-Sexton Abdu F Azad Rickettsia typhi possesses phospholipase A2 enzymes that are involved in infection of host cells.
description	The long-standing proposal that phospholipase A2 (PLA2) enzymes are involved in rickettsial infection of host cells has been given support by the recent characterization of a patatin phospholipase (Pat2) with PLA2 activity from the pathogens Rickettsia prowazekii and R. typhi. However, pat2 is not encoded in all Rickettsia genomes; yet another uncharacterized patatin (Pat1) is indeed ubiquitous. Here, evolutionary analysis of both patatins across 46 Rickettsia genomes revealed 1) pat1 and pat2 loci are syntenic across all genomes, 2) both Pat1 and Pat2 do not contain predicted Sec-dependent signal sequences, 3) pat2 has been pseudogenized multiple times in rickettsial evolution, and 4) ubiquitous pat1 forms two divergent groups (pat1A and pat1B) with strong evidence for recombination between pat1B and plasmid-encoded homologs. In light of these findings, we extended the characterization of R. typhi Pat1 and Pat2 proteins and determined their role in the infection process. As previously demonstrated for Pat2, we determined that 1) Pat1 is expressed and secreted into the host cytoplasm during R. typhi infection, 2) expression of recombinant Pat1 is cytotoxic to yeast cells, 3) recombinant Pat1 possesses PLA2 activity that requires a host cofactor, and 4) both Pat1 cytotoxicity and PLA2 activity were reduced by PLA2 inhibitors and abolished by site-directed mutagenesis of catalytic Ser/Asp residues. To ascertain the role of Pat1 and Pat2 in R. typhi infection, antibodies to both proteins were used to pretreat rickettsiae. Subsequent invasion and plaque assays both indicated a significant decrease in R. typhi infection compared to that by pre-immune IgG. Furthermore, antibody-pretreatment of R. typhi blocked/delayed phagosomal escapes. Together, these data suggest both enzymes are involved early in the infection process. Collectively, our study suggests that R. typhi utilizes two evolutionary divergent patatin phospholipases to support its intracellular life cycle, a mechanism distinguishing it from other rickettsial species.
format	article
author	M Sayeedur Rahman Joseph J Gillespie Simran Jeet Kaur Khandra T Sears Shane M Ceraul Magda Beier-Sexton Abdu F Azad
author_facet	M Sayeedur Rahman Joseph J Gillespie Simran Jeet Kaur Khandra T Sears Shane M Ceraul Magda Beier-Sexton Abdu F Azad
author_sort	M Sayeedur Rahman
title	Rickettsia typhi possesses phospholipase A2 enzymes that are involved in infection of host cells.
title_short	Rickettsia typhi possesses phospholipase A2 enzymes that are involved in infection of host cells.
title_full	Rickettsia typhi possesses phospholipase A2 enzymes that are involved in infection of host cells.
title_fullStr	Rickettsia typhi possesses phospholipase A2 enzymes that are involved in infection of host cells.
title_full_unstemmed	Rickettsia typhi possesses phospholipase A2 enzymes that are involved in infection of host cells.
title_sort	rickettsia typhi possesses phospholipase a2 enzymes that are involved in infection of host cells.
publisher	Public Library of Science (PLoS)
publishDate	2013
url	https://doaj.org/article/a9dec9b022fd4010afd1f888fee6c68a
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Rickettsia typhi possesses phospholipase A2 enzymes that are involved in infection of host cells.

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