Adhesion, Invasion, and Agglutination Mediated by Two Trimeric Autotransporters in the Human Uropathogen Proteus mirabilis

ABSTRACT Fimbriae of the human uropathogen Proteus mirabilis are the only characterized surface proteins that contribute to its virulence by mediating adhesion and invasion of the uroepithelia. PMI2122 (AipA) and PMI2575 (TaaP) are annotated in the genome of strain HI4320 as trimeric autotransporters with “adhesin-like” and “agglutinating adhesin-like” properties, respectively. The C-terminal 62 amino acids (aa) in AipA and 76 aa in TaaP are homologous to the translocator domains of YadA from Yersinia enterocolitica and Hia from Haemophilus influenzae. Comparative protein modeling using the Hia three-dimensional structure as a template predicted that each of these domains would contain four antiparallel beta sheets and that they formed homotrimers. Recombinant AipA and TaaP were seen as ∼28 kDa and ∼78 kDa, respectively, in Escherichia coli, and each also formed high-molecular-weight homotrimers, thus supporting this model. E. coli synthesizing AipA or TaaP bound to extracellular matrix proteins with a 10- to 60-fold-higher level of affinity than the control strain. Inactivation of aipA in P. mirabilis strains significantly (P < 0.01) reduced the mutants' ability to adhere to or invade HEK293 cell monolayers, and the functions were restored upon complementation. A 51-aa-long invasin region in the AipA passenger domain was required for this function. E. coli expressing TaaP mediated autoagglutination, and a taaP mutant of P. mirabilis showed significantly (P < 0.05) more reduced aggregation than HI4320. Gly-247 in AipA and Gly-708 in TaaP were indispensable for trimerization and activity. AipA and TaaP individually offered advantages to P. mirabilis in a murine model. This is the first report characterizing trimeric autotransporters in P. mirabilis as afimbrial surface adhesins and autoagglutinins.

Download Full-text

AatA Is a Novel Autotransporter and Virulence Factor of Avian Pathogenic Escherichia coli

Infection and Immunity ◽

10.1128/iai.00513-09 ◽

2009 ◽

Vol 78 (3) ◽

pp. 898-906 ◽

Cited By ~ 30

Author(s):

Ganwu Li ◽

Yaping Feng ◽

Subhashinie Kariyawasam ◽

Kelly A. Tivendale ◽

Yvonne Wannemuehler ◽

...

Keyword(s):

Escherichia Coli ◽

Amino Acid ◽

Chicken Embryo Fibroblast ◽

Three Dimensional ◽

Dimensional Structure ◽

Virulence Plasmid ◽

Passenger Domain ◽

Reading Frame ◽

E Coli ◽

Amino Acid Signal Peptide

ABSTRACT Autotransporters (AT) are widespread in Gram-negative bacteria, and many of them are involved in virulence. An open reading frame (APECO1_O1CoBM96) encoding a novel AT was located in the pathogenicity island of avian pathogenic Escherichia coli (APEC) O1's virulence plasmid, pAPEC-O1-ColBM. This 3.5-kb APEC autotransporter gene (aatA) is predicted to encode a 123.7-kDa protein with a 25-amino-acid signal peptide, an 857-amino-acid passenger domain, and a 284-amino-acid β domain. The three-dimensional structure of AatA was also predicted by the threading method using the I-TASSER online server and then was refined using four-body contact potentials. Molecular analysis of AatA revealed that it is translocated to the cell surface, where it elicits antibody production in infected chickens. Gene prevalence analysis indicated that aatA is strongly associated with E. coli from avian sources but not with E. coli isolated from human hosts. Also, AatA was shown to enhance adhesion of APEC to chicken embryo fibroblast cells and to contribute to APEC virulence.

Download Full-text

Structural Role of rRNAs on the Ribosomal Subunits from E. Coli by Scanning Transmission Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100098629 ◽

1981 ◽

Vol 39 ◽

pp. 424-425

Author(s):

M. Boublik ◽

N. Robakis ◽

J.S. Wall

Keyword(s):

Three Dimensional ◽

Uranyl Acetate ◽

Dimensional Structure ◽

Electron Microscopic ◽

Ribosomal Subunits ◽

E Coli ◽

Freeze Dried ◽

16S Rna ◽

Scanning Transmission ◽

And Function

The three-dimensional structure and function of biological supramolecular complexes are, in general, determined and stabilized by conformation and interactions of their macromolecular components. In the case of ribosomes, it has been suggested that one of the functions of ribosomal RNAs is to act as a scaffold maintaining the shape of the ribosomal subunits. In order to investigate this question, we have conducted a comparative TEM and STEM study of the structure of the small 30S subunit of E. coli and its 16S RNA.The conventional electron microscopic imaging of nucleic acids is performed by spreading them in the presence of protein or detergent; the particles are contrasted by electron dense solution (uranyl acetate) or by shadowing with metal (tungsten). By using the STEM on freeze-dried specimens we have avoided the shearing forces of the spreading, and minimized both the collapse of rRNA due to air drying and the loss of resolution due to staining or shadowing. Figure 1, is a conventional (TEM) electron micrograph of 30S E. coli subunits contrasted with uranyl acetate.

Download Full-text

Three-Dimensional Structure of the HTLV-II Matrix Protein and Comparative Analysis of Matrix Proteins from the Different Classes of Pathogenic Human Retroviruses

Journal of Molecular Biology ◽

10.1006/jmbi.1996.0700 ◽

1996 ◽

Vol 264 (5) ◽

pp. 1117-1131 ◽

Cited By ~ 45

Author(s):

Allyson M. Christensen ◽

Michael A. Massiah ◽

Brian G. Turner ◽

Wesley I. Sundquist ◽

Michael F. Summers

Keyword(s):

Comparative Analysis ◽

Matrix Protein ◽

Three Dimensional ◽

Matrix Proteins ◽

Dimensional Structure ◽

Three Dimensional Structure

Download Full-text

RNA minihelices as model substrates for ATP/CTP:tRNA nucleotidyltransferase

Biochemical Journal ◽

10.1042/bj3270847 ◽

1997 ◽

Vol 327 (3) ◽

pp. 847-851 ◽

Cited By ~ 16

Author(s):

Zengji LI ◽

Yue SUN ◽

L. David THURLOW

Keyword(s):

Escherichia Coli ◽

Saccharomyces Cerevisiae ◽

Three Dimensional ◽

Dimensional Structure ◽

Single Base ◽

Three Dimensional Structure ◽

E Coli ◽

Base Identity

Twenty-one RNA minihelices, resembling the coaxially stacked acceptor- /T-stems and T-loop found along the top of a tRNA's three-dimensional structure, were synthesized and used as substrates for ATP/CTP:tRNA nucleotidyltransferases from Escherichia coli and Saccharomyces cerevisiae. The sequence of nucleotides in the loop varied at positions corresponding to residues 56, 57 and 58 in the T-loop of a tRNA. All minihelices were substrates for both enzymes, and the identity of bases in the loop affected the interaction. In general, RNAs with purines in the loop were better substrates than those with pyrimidines, although no single base identity absolutely determined the effectiveness of the RNA as substrate. RNAs lacking bases near the 5ʹ-end were good substrates for the E. coli enzyme, but were poor substrates for that from yeast. The apparent Km values for selected minihelices were 2-3 times that for natural tRNA, and values for apparent Vmax were lowered 5-10-fold.

Download Full-text

Three-Dimensional Structure of Membrane and Surface Proteins

Annual Review of Biochemistry ◽

10.1146/annurev.bi.53.070184.003115 ◽

1984 ◽

Vol 53 (1) ◽

pp. 595-623 ◽

Cited By ~ 641

Author(s):

D Eisenberg

Keyword(s):

Three Dimensional ◽

Surface Proteins ◽

Dimensional Structure ◽

Three Dimensional Structure

Download Full-text

Three-dimensional structure of β-galactosidase from E. coli.

Nature ◽

10.1038/369761a0 ◽

1994 ◽

Vol 369 (6483) ◽

pp. 761-766 ◽

Cited By ~ 432

Author(s):

R. H. Jacobson ◽

X.-J. Zhang ◽

R. F. DuBose ◽

B. W. Matthews

Keyword(s):

Three Dimensional ◽

Dimensional Structure ◽

Three Dimensional Structure ◽

E Coli

Download Full-text

Three-dimensional structure of the 67K N-terminal fragment of E. coli DNA topoisomerase I

Nature ◽

10.1038/367138a0 ◽

1994 ◽

Vol 367 (6459) ◽

pp. 138-146 ◽

Cited By ~ 221

Author(s):

Christopher D. Lima ◽

James C. Wang ◽

Alfonso Mondragón

Keyword(s):

Topoisomerase I ◽

Three Dimensional ◽

Dimensional Structure ◽

Dna Topoisomerase I ◽

Dna Topoisomerase ◽

Three Dimensional Structure ◽

E Coli ◽

Terminal Fragment

Download Full-text

The Ribosome - Three-Dimensional Structure and Ligand-Binding Studies

Microscopy and Microanalysis ◽

10.1017/s1431927600024934 ◽

1998 ◽

Vol 4 (S2) ◽

pp. 962-963

Author(s):

J. Frank ◽

P. Penczek ◽

A. Malhotra ◽

I. Gabashvili ◽

R. Grassucci ◽

...

Keyword(s):

State Of The Art ◽

Three Dimensional ◽

Dimensional Structure ◽

Conformational Heterogeneity ◽

Binding Studies ◽

E Coli ◽

Cryo Electron Microscopy ◽

Protein Synthesis Initiation ◽

Successful Technique ◽

Electron Microscopes

To date, cryo-electron microscopy has become the most successful technique for exploring the structure of the ribosome and for studying binding positions of its various ligands, with the resolution slowly extending toward 10 Å. Obstacles in the attempts to improve resolution are the limited stability and coherence of the electron microscope, the statistics of data collection, and the conformational heterogeneity of the specimen. The last factor in this list proved to be the reason why it has been difficult to go past 18-20 Å with many specimens despite the use of state-of-the-art electron microscopes and inclusion of tens of thousand of projections.A breakthrough has been achieved with a protein synthesis initiation-like complex in which mRNA and fMet-tRNA is bound to the E. coli ribosome. The high occupancy and extraordinary conformational homogeneity of this specimen has enabled us to reach a resolution of 15 Å.

Download Full-text