scholarly journals Dating Alphaproteobacteria evolution with eukaryotic fossils

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sishuo Wang ◽  
Haiwei Luo
Keyword(s):  
Terrestrial Ecosystems ◽  
Symbiotic Bacteria ◽  
Divergence Times ◽  
Intracellular Bacteria ◽  
Testing Hypotheses ◽  
Obligate Intracellular ◽  
Unicellular Eukaryotes ◽  
Rapid Divergence ◽  
Obligate Intracellular Bacteria ◽  
Traditional Strategy

AbstractElucidating the timescale of the evolution of Alphaproteobacteria, one of the most prevalent microbial lineages in marine and terrestrial ecosystems, is key to testing hypotheses on their co-evolution with eukaryotic hosts and Earth’s systems, which, however, is largely limited by the scarcity of bacterial fossils. Here, we incorporate eukaryotic fossils to date the divergence times of Alphaproteobacteria, based on the mitochondrial endosymbiosis that mitochondria evolved from an alphaproteobacterial lineage. We estimate that Alphaproteobacteria arose ~1900 million years (Ma) ago, followed by rapid divergence of their major clades. We show that the origin of Rickettsiales, an order of obligate intracellular bacteria whose hosts are mostly animals, predates the emergence of animals for ~700 Ma but coincides with that of eukaryotes. This, together with reconstruction of ancestral hosts, strongly suggests that early Rickettsiales lineages had established previously underappreciated interactions with unicellular eukaryotes. Moreover, the mitochondria-based approach displays higher robustness to uncertainties in calibrations compared with the traditional strategy using cyanobacterial fossils. Further, our analyses imply the potential of dating the (bacterial) tree of life based on endosymbiosis events, and suggest that previous applications using divergence times of the modern hosts of symbiotic bacteria to date bacterial evolution might need to be revisited.

scholarly journals Dating Alphaproteobacteria evolution with eukaryotic fossils

2020 ◽  
Author(s):  
Sishuo Wang ◽  
Haiwei Luo
Keyword(s):  
Tree Of Life ◽  
Symbiotic Bacteria ◽  
Divergence Times ◽  
Intracellular Bacteria ◽  
Testing Hypotheses ◽  
Obligate Intracellular ◽  
Unicellular Eukaryotes ◽  
Rapid Divergence ◽  
Obligate Intracellular Bacteria ◽  
Traditional Strategy

AbstractElucidating the timescale of evolution of bacteria is key to testing hypotheses on their co-evolution with eukaryotic hosts, which, however, is largely limited by the scarcity of bacterial fossils. Here, we incorporate eukaryotic fossils to date the divergence times of Alphaproteobacteria, based on the endosymbiosis theory that mitochondria evolved from an alphaproteobacterial lineage. We estimate that Alphaproteobacteria arose ~1900 million years (Ma) ago, followed by rapid divergence of their major clades. We show that the origin of Rickettsiales, an order of obligate intracellular bacteria whose hosts are mostly animals, predates the emergence of animals for ~700 Ma but coincides with that of eukaryotes. This, together with reconstruction of ancestral hosts, strongly suggests that early Rickettsiales lineages had established previously underappreciated interactions with unicellular eukaryotes. Our mitochondria-based approach displays higher precision and robustness to uncertainties compared with the traditional strategy using cyanobacterial fossils, and suggests that previous applications using divergence times of the modern hosts of symbiotic bacteria to date the bacterial tree of life may need to be revisited.

scholarly journals The growing repertoire of genetic tools for dissecting chlamydial pathogenesis

2021 ◽  
Author(s):  
Arkaprabha Banerjee ◽  
David E Nelson
Keyword(s):  
Genetic Engineering ◽  
Intracellular Bacteria ◽  
Human Pathogens ◽  
Pathogenic Potential ◽  
Host Preferences ◽  
Genetic Tools ◽  
Obligate Intracellular ◽  
Obligate Intracellular Bacteria ◽  
Multiple Species

Abstract Multiple species of obligate intracellular bacteria in the genus Chlamydia are important veterinary and/or human pathogens. These pathogens all share similar biphasic developmental cycles and transition between intracellular vegetative reticulate bodies and infectious elementary forms, but vary substantially in their host preferences and pathogenic potential. A lack of tools for genetic engineering of these organisms has long been an impediment to the study of their biology and pathogenesis. However, the refinement of approaches developed in C. trachomatis over the last ten years, and adaptation of some of these approaches to other Chlamydia spp. in just the last few years, has opened exciting new possibilities for studying this ubiquitous group of important pathogens.

scholarly journals Initial Characterization of the Two ClpP Paralogs ofChlamydia trachomatisSuggests Unique Functionality for Each

2018 ◽  
Vol 201 (2) ◽  
Author(s):  
Nicholas A. Wood ◽  
Krystal Y. Chung ◽  
Amanda M. Blocker ◽  
Nathalia Rodrigues de Almeida ◽  
Martin Conda-Sheridan ◽  
...  
Keyword(s):  
Host Cells ◽  
Developmental Cycle ◽  
Intracellular Bacteria ◽  
Clp Protease ◽  
Content Type ◽  
Sexually Transmitted ◽  
Obligate Intracellular ◽  
Developmental Form ◽  
Obligate Intracellular Bacteria

ABSTRACTMembers ofChlamydiaare obligate intracellular bacteria that differentiate between two distinct functional and morphological forms during their developmental cycle, elementary bodies (EBs) and reticulate bodies (RBs). EBs are nondividing small electron-dense forms that infect host cells. RBs are larger noninfectious replicative forms that develop within a membrane-bound vesicle, termed an inclusion. Given the unique properties of each developmental form of this bacterium, we hypothesized that the Clp protease system plays an integral role in proteomic turnover by degrading specific proteins from one developmental form or the other.Chlamydiaspp. have five uncharacterizedclpgenes,clpX,clpC, twoclpPparalogs, andclpB. In other bacteria, ClpC and ClpX are ATPases that unfold and feed proteins into the ClpP protease to be degraded, and ClpB is a deaggregase. Here, we focused on characterizing the ClpP paralogs. Transcriptional analyses and immunoblotting determined that these genes are expressed midcycle. Bioinformatic analyses of these proteins identified key residues important for activity. Overexpression of inactiveclpPmutants inChlamydiaspp. suggested independent function of each ClpP paralog. To further probe these differences, we determined interactions between the ClpP proteins using bacterial two-hybrid assays and native gel analysis of recombinant proteins. Homotypic interactions of the ClpP proteins, but not heterotypic interactions between the ClpP paralogs, were detected. Interestingly, protease activity of ClpP2, but not ClpP1, was detectedin vitro. This activity was stimulated by antibiotics known to activate ClpP, which also blocked chlamydial growth. Our data suggest the chlamydial ClpP paralogs likely serve distinct and critical roles in this important pathogen.IMPORTANCEChlamydia trachomatisis the leading cause of preventable infectious blindness and of bacterial sexually transmitted infections worldwide. Chlamydiae are developmentally regulated obligate intracellular pathogens that alternate between two functional and morphologic forms, with distinct repertoires of proteins. We hypothesize that protein degradation is a critical aspect to the developmental cycle. A key system involved in protein turnover in bacteria is the Clp protease system. Here, we characterized the two chlamydial ClpP paralogs by examining their expression inChlamydiaspp., their ability to oligomerize, and their proteolytic activity. This work will help understand the evolutionarily diverse Clp proteases in the context of intracellular organisms, which may aid in the study of other clinically relevant intracellular bacteria.

Infections caused by obligate intracellular bacteria

2017 ◽  
Author(s):  
Philippa C. Matthews
Keyword(s):  
Clinical Significance ◽  
Classification System ◽  
Q Fever ◽  
Intracellular Bacteria ◽  
Rickettsial Infection ◽  
Obligate Intracellular ◽  
Treatment And Prevention ◽  
Clinical Syndromes ◽  
Obligate Intracellular Bacteria ◽  
The Tropics

This chapter consists of short notes, diagrams, and tables to summarize infections caused by obligate intracellular bacteria. The chapter begins with a classification system to divide these organisms into Rickettsia, Anaplasma, Chlamydia, Coxiella, and Bartonella species. Separate sections then follow on the infections of most clinical significance for the tropics and subtropics, including the typhus group (caused by rickettsial infection) and Q fever. For ease of reference, each topic is broken down into sections, including classification, epidemiology, microbiology, pathophysiology, clinical syndromes, diagnosis, treatment, and prevention.

scholarly journals Vaccine Design and Vaccination Strategies against Rickettsiae

Vaccines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 896
Author(s):  
Anke Osterloh
Keyword(s):  
Protective Immunity ◽  
Vaccine Development ◽  
Intracellular Bacteria ◽  
Obligate Intracellular ◽  
Vaccination Strategies ◽  
The Past ◽  
Rickettsial Infections ◽  
Causative Agents ◽  
Prophylactic Vaccines ◽  
Obligate Intracellular Bacteria

Rickettsioses are febrile, potentially lethal infectious diseases that are a serious health threat, especially in poor income countries. The causative agents are small obligate intracellular bacteria, rickettsiae. Rickettsial infections are emerging worldwide with increasing incidence and geographic distribution. Nonetheless, these infections are clearly underdiagnosed because methods of diagnosis are still limited and often not available. Another problem is that the bacteria respond to only a few antibiotics, so delayed or wrong antibiotic treatment often leads to a more severe outcome of the disease. In addition to that, the development of antibiotic resistance is a serious threat because alternative antibiotics are missing. For these reasons, prophylactic vaccines against rickettsiae are urgently needed. In the past years, knowledge about protective immunity against rickettsiae and immunogenic determinants has been increasing and provides a basis for vaccine development against these bacterial pathogens. This review provides an overview of experimental vaccination approaches against rickettsial infections and perspectives on vaccination strategies.

Rickettsioses

2020 ◽  
pp. 1230-1251
Author(s):  
Karolina Griffiths ◽  
Carole Eldin ◽  
Didier Raoult ◽  
Philippe Parola
Keyword(s):  
Scrub Typhus ◽  
Spotted Fever ◽  
Intracellular Bacteria ◽  
Spotted Fever Group ◽  
Orientia Tsutsugamushi ◽  
Obligate Intracellular ◽  
Metabolic Characteristics ◽  
The Past ◽  
Life Threatening ◽  
Obligate Intracellular Bacteria

Rickettsioses are mild to life-threatening zoonoses caused by obligate intracellular bacteria of the order Rickettsiales (family Rickettsiaceae). Arthropods, including ticks, fleas, and mites, are implicated as their vectors, reservoirs, or amplifiers. With an increasing number of new pathogens and recognition of new pathogenicity and affected geographical areas over the past few decades, there is a better understanding of the scope and importance of these pathogens, particularly as a paradigm to understanding emerging and remerging infections. The taxonomy has undergone numerous changes, with now three main groups classified as rickettsioses according to morphological, antigenic and metabolic characteristics: (1) Rickettsioses due to the bacteria of the genus Rickettsia, including the spotted fever group, typhus groups (Rickettsiaceae), (2) Ehrlichioses and Anaplasmoses due to bacteria of the Anaplasmataceae and (3) scrub typhus due to Orientia tsutsugamushi.

scholarly journals Bacteria of the genus Anaplasma – characteristics of Anaplasma and their vectors: a review

2008 ◽  
Vol 53 (No. 11) ◽  
pp. 573-584 ◽  
Author(s):  
A. Rymaszewska ◽  
S. Grenda
Keyword(s):  
Domestic Animals ◽  
Farm Animals ◽  
Intracellular Bacteria ◽  
Obligate Intracellular ◽  
The World ◽  
Pathogenic Activity ◽  
Obligate Intracellular Bacteria

Over recent years, there has been a growing interest in bacteria from the genus <I>Anaplasma</I>, especially the species <I>A. marginale, A. ovis</I> and <I>A. phagocytophilum</I>. It is connected with the pathogenic activity of these bacteria in farm animals, and also, though to a lesser degree, in humans. Anaplasmosis, a disease caused by various species of anaplasma, is an especially important issue for animal breeders. The main vectors of the <I>Anaplasma</I> bacteria are ticks, common arachnida occurring everywhere in the world, especially the genera <I>Ixodes, Dermacentor, Rhipicephalus</I> and<I> Amblyomma</I>. The genus <I>Anaplasma</I> includes obligate intracellular bacteria, parasitizing in the vacuoles of cells in eukaryotic hosts. <I>A. marginale, A. centrale, A. ovis and<I>A. bovis</I> are obligate intracellular bacteria parasitizing in erythrocytes and monocytes of higher vertebrates, mostly ruminants. <I> A. platys</I> is mainly a pathogen of canines (displaying tropism to thrombocytes) and the species <I>A. phagocytophilum</I> (displaying tropism to granulocytes) is pathogenic to people and domestic animals. In this paper we present characteristics and differentiation of six species of the genus <I>Anaplasma</I> and their vectors in the world.

scholarly journals Manipulation of Host Cholesterol by Obligate Intracellular Bacteria

2017 ◽  
Vol 7 ◽  
Author(s):  
Dhritiman Samanta ◽  
Minal Mulye ◽  
Tatiana M. Clemente ◽  
Anna V. Justis ◽  
Stacey D. Gilk
Keyword(s):  
Intracellular Bacteria ◽  
Obligate Intracellular ◽  
Obligate Intracellular Bacteria
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