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Collagen-like proteins in pathogenic E. coli strains.

Ghosh N, McKillop TJ, Jowitt TA, Howard M, Davies H, Holmes DF, Roberts IS, Bella J - PLoS ONE (2012)

Bottom Line: Under the electron microscope, collagen-like proteins from E. coli O157:H7 show a dumbbell shape, with two globular domains joined by a hinged stalk.This morphology is consistent with their likely role as trimeric phage side-tail proteins that participate in the attachment of phage particles to E. coli target cells, either directly or through assembly with other phage tail proteins.Thus, collagen-like proteins in enterohaemorrhagic E. coli genomes may have a direct role in the dissemination of virulence-related genes through infection of harmless strains by induced bacteriophages.

View Article: PubMed Central - PubMed

Affiliation: Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom.

ABSTRACT
The genome sequences of enterohaemorrhagic E. coli O157:H7 strains show multiple open-reading frames with collagen-like sequences that are absent from the common laboratory strain K-12. These putative collagens are included in prophages embedded in O157:H7 genomes. These prophages carry numerous genes related to strain virulence and have been shown to be inducible and capable of disseminating virulence factors by horizontal gene transfer. We have cloned two collagen-like proteins from E. coli O157:H7 into a laboratory strain and analysed the structure and conformation of the recombinant proteins and several of their constituting domains by a variety of spectroscopic, biophysical, and electron microscopy techniques. We show that these molecules exhibit many of the characteristics of vertebrate collagens, including trimer formation and the presence of a collagen triple helical domain. They also contain a C-terminal trimerization domain, and a trimeric α-helical coiled-coil domain with an unusual amino acid sequence almost completely lacking leucine, valine or isoleucine residues. Intriguingly, these molecules show high thermal stability, with the collagen domain being more stable than those of vertebrate fibrillar collagens, which are much longer and post-translationally modified. Under the electron microscope, collagen-like proteins from E. coli O157:H7 show a dumbbell shape, with two globular domains joined by a hinged stalk. This morphology is consistent with their likely role as trimeric phage side-tail proteins that participate in the attachment of phage particles to E. coli target cells, either directly or through assembly with other phage tail proteins. Thus, collagen-like proteins in enterohaemorrhagic E. coli genomes may have a direct role in the dissemination of virulence-related genes through infection of harmless strains by induced bacteriophages.

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Related in: MedlinePlus

Coiled-coiled predictions for the amino acid sequences of (A) EPclA (ECs2717) and (B) EPclB (ECs1228), using the PCoils[70] and Marcoil[71] algorithms.The graphs indicate regions of high probability for α-helical coiled-coil formation. Three different sequence window sizes were used with the PCoils algorithm: 14, 21 and 28 residues. Two different matrices were used in Marcoil: 9FAM, and MTK-based.
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pone-0037872-g002: Coiled-coiled predictions for the amino acid sequences of (A) EPclA (ECs2717) and (B) EPclB (ECs1228), using the PCoils[70] and Marcoil[71] algorithms.The graphs indicate regions of high probability for α-helical coiled-coil formation. Three different sequence window sizes were used with the PCoils algorithm: 14, 21 and 28 residues. Two different matrices were used in Marcoil: 9FAM, and MTK-based.

Mentions: The region between the predicted PfN and Col domains in the most common architectures, EPclA and EPclB, shows an unusual low-complexity sequence with predominance of Ala (32%), Ser (19%) and Glu (13%) amino acids that often appear in tandems or in stretches of up to four consecutive identical residues (Figure 1). Different coiled-coil predicting algorithms (PCoils, Marcoil, MultiCoil) give high scores for the region between residues 101 and 245 in both EPclA and EPclB (Figure 2). This region includes the low-complexity sequence between the PfN and Col domains plus the last 34 residues of PfN, and shows a loose seven-residue Ala-X-X-Ala/Ser-X-X-Ser periodicity, where residues in the X positions are often charged. On account of the coiled-coil predictions we will refer to the low-complexity region between PfN and Col as the PCoil domain. The MultiCoil and SCORER 2.0 prediction algorithms favour a trimeric rather than dimeric coiled-coil structure for PCoil. Secondary structure prediction by Jpred3 suggests that the PfN domain has mainly a β-sheet structure for the first 80 residues and some α-helical conformation from residues 90 onwards, whereas the PCoil region is predicted to be mainly α-helical. Jpred3 does not predict any secondary structure for the PfC domains (data not shown).


Collagen-like proteins in pathogenic E. coli strains.

Ghosh N, McKillop TJ, Jowitt TA, Howard M, Davies H, Holmes DF, Roberts IS, Bella J - PLoS ONE (2012)

Coiled-coiled predictions for the amino acid sequences of (A) EPclA (ECs2717) and (B) EPclB (ECs1228), using the PCoils[70] and Marcoil[71] algorithms.The graphs indicate regions of high probability for α-helical coiled-coil formation. Three different sequence window sizes were used with the PCoils algorithm: 14, 21 and 28 residues. Two different matrices were used in Marcoil: 9FAM, and MTK-based.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3368898&req=5

pone-0037872-g002: Coiled-coiled predictions for the amino acid sequences of (A) EPclA (ECs2717) and (B) EPclB (ECs1228), using the PCoils[70] and Marcoil[71] algorithms.The graphs indicate regions of high probability for α-helical coiled-coil formation. Three different sequence window sizes were used with the PCoils algorithm: 14, 21 and 28 residues. Two different matrices were used in Marcoil: 9FAM, and MTK-based.
Mentions: The region between the predicted PfN and Col domains in the most common architectures, EPclA and EPclB, shows an unusual low-complexity sequence with predominance of Ala (32%), Ser (19%) and Glu (13%) amino acids that often appear in tandems or in stretches of up to four consecutive identical residues (Figure 1). Different coiled-coil predicting algorithms (PCoils, Marcoil, MultiCoil) give high scores for the region between residues 101 and 245 in both EPclA and EPclB (Figure 2). This region includes the low-complexity sequence between the PfN and Col domains plus the last 34 residues of PfN, and shows a loose seven-residue Ala-X-X-Ala/Ser-X-X-Ser periodicity, where residues in the X positions are often charged. On account of the coiled-coil predictions we will refer to the low-complexity region between PfN and Col as the PCoil domain. The MultiCoil and SCORER 2.0 prediction algorithms favour a trimeric rather than dimeric coiled-coil structure for PCoil. Secondary structure prediction by Jpred3 suggests that the PfN domain has mainly a β-sheet structure for the first 80 residues and some α-helical conformation from residues 90 onwards, whereas the PCoil region is predicted to be mainly α-helical. Jpred3 does not predict any secondary structure for the PfC domains (data not shown).

Bottom Line: Under the electron microscope, collagen-like proteins from E. coli O157:H7 show a dumbbell shape, with two globular domains joined by a hinged stalk.This morphology is consistent with their likely role as trimeric phage side-tail proteins that participate in the attachment of phage particles to E. coli target cells, either directly or through assembly with other phage tail proteins.Thus, collagen-like proteins in enterohaemorrhagic E. coli genomes may have a direct role in the dissemination of virulence-related genes through infection of harmless strains by induced bacteriophages.

View Article: PubMed Central - PubMed

Affiliation: Manchester Interdisciplinary Biocentre, University of Manchester, Manchester, United Kingdom.

ABSTRACT
The genome sequences of enterohaemorrhagic E. coli O157:H7 strains show multiple open-reading frames with collagen-like sequences that are absent from the common laboratory strain K-12. These putative collagens are included in prophages embedded in O157:H7 genomes. These prophages carry numerous genes related to strain virulence and have been shown to be inducible and capable of disseminating virulence factors by horizontal gene transfer. We have cloned two collagen-like proteins from E. coli O157:H7 into a laboratory strain and analysed the structure and conformation of the recombinant proteins and several of their constituting domains by a variety of spectroscopic, biophysical, and electron microscopy techniques. We show that these molecules exhibit many of the characteristics of vertebrate collagens, including trimer formation and the presence of a collagen triple helical domain. They also contain a C-terminal trimerization domain, and a trimeric α-helical coiled-coil domain with an unusual amino acid sequence almost completely lacking leucine, valine or isoleucine residues. Intriguingly, these molecules show high thermal stability, with the collagen domain being more stable than those of vertebrate fibrillar collagens, which are much longer and post-translationally modified. Under the electron microscope, collagen-like proteins from E. coli O157:H7 show a dumbbell shape, with two globular domains joined by a hinged stalk. This morphology is consistent with their likely role as trimeric phage side-tail proteins that participate in the attachment of phage particles to E. coli target cells, either directly or through assembly with other phage tail proteins. Thus, collagen-like proteins in enterohaemorrhagic E. coli genomes may have a direct role in the dissemination of virulence-related genes through infection of harmless strains by induced bacteriophages.

Show MeSH
Related in: MedlinePlus