We use cookies to understand how you use our site and to improve your experience. This includes personalizing content and advertising. To learn more, click here. By continuing to use our site, you accept our use of cookies. Cookie Policy.

Features Partner Sites Information LinkXpress hp
Sign In
Advertise with Us
LGC Clinical Diagnostics

Download Mobile App




Researchers Pinpoint Binding Site for Clostridium difficile Binary Toxin

By LabMedica International staff writers
Posted on 21 Jun 2015
Print article
Image: Bacterial toxins usually exert their full deadly effect in the host cell\'s interior. The toxins overcome the cell membrane by binding to a surface receptor, which conveys them into the cell\'s interior (Photo courtesy of Dr. Panagiotis Papatheodorou, University of Freiburg).
Image: Bacterial toxins usually exert their full deadly effect in the host cell\'s interior. The toxins overcome the cell membrane by binding to a surface receptor, which conveys them into the cell\'s interior (Photo courtesy of Dr. Panagiotis Papatheodorou, University of Freiburg).
A team of molecular microbiologists has located the site where the bacterium Clostridium difficile's binary toxin binds to intestinal cells' LSR (lipolysis-stimulated lipoprotein receptor) protein and triggers a mechanism that results in the invasion of the host cells by the bacteria.

Clostridium difficile is a serious intestinal pathogen that can cause severe diarrhea and life-threatening intestinal infections especially after long-term treatment with antibiotics. The bacteria produce the binary, actin ADP-ribosylating toxin CDT (Clostridium difficile transferase). While CDT can lead to death of the host cells through collapse of the actin cytoskeleton, low doses of CDT result in the formation of microtubule-based protrusions on the cell surface that increase the adherence and colonization of C. difficile.

Investigators at the University of Freiburg (Germany) examined how CDT binds to its host cell LSR. They reported in the April 16, 2015, online edition of the Journal of Biological Chemistry that CDT interacted with the extracellular, Ig-like domain of LSR with an affinity in the nanomolar range. They identified LSR splice variants in the colon carcinoma cell line HCT116 and disrupted the LSR gene in these cells by applying CRISPR-Cas9 technology.

CRISPRs (clustered regularly interspaced short palindromic repeats) are segments of prokaryotic DNA containing short repetitions of base sequences. Each repetition is followed by short segments of "spacer DNA" from previous exposures to a bacterial virus or plasmid. CRISPRs are found in approximately 40% of sequenced bacteria genomes and 90% of sequenced archaea. CRISPRs are often associated with cas genes that code for proteins related to CRISPRs. The CRISPR/Cas complex comprises a prokaryotic immune system that confers resistance to foreign genetic elements such as plasmids and phages and provides a form of acquired immunity. Since 2013, the CRISPR/Cas system has been used in research for gene editing (adding, disrupting, or changing the sequence of specific genes) and gene regulation. By delivering the Cas9 protein and appropriate guide RNAs into a cell, the organism's genome can be cut at any desired location.

LSR segments created by the CRISPR/Cas technique were expressed ectopically in cells lacking the LSR gene. Results of these experiments showed that intracellular parts of LSR were not essential for plasma membrane targeting of the receptor and cellular uptake of CDT. Furthermore, by generating a series of N- and C-terminal truncations of the binding component of CDT (CDTb), they found that amino acids 757 to 866 of CDTb were sufficient for binding to LSR.

"In the future, it should be possible to block these areas in the toxin and receptor in order to prevent the toxin from entering the host cell," said senior author Dr. Panagiotis Papatheodorou, professor of biology at the University of Freiburg.

Related Links:

University of Freiburg


New
Gold Member
Pneumocystis Jirovecii Detection Kit
Pneumocystis Jirovecii Real Time RT-PCR Kit
Automated Blood Typing System
IH-500 NEXT
New
Histamine ELISA
Histamine ELISA
New
Gold Member
Syphilis Screening Test
VDRL Antigen MR

Print article

Channels

Clinical Chemistry

view channel
Image: The new saliva-based test for heart failure measures two biomarkers in about 15 minutes (Photo courtesy of Trey Pittman)

POC Saliva Testing Device Predicts Heart Failure in 15 Minutes

Heart failure is a serious condition where the heart muscle is unable to pump sufficient oxygen-rich blood throughout the body. It ranks as a major cause of death globally and is particularly fatal for... Read more

Hematology

view channel
Image: The smartphone technology measures blood hemoglobin levels from a digital photo of the inner eyelid (Photo courtesy of Purdue University)

First-Of-Its-Kind Smartphone Technology Noninvasively Measures Blood Hemoglobin Levels at POC

Blood hemoglobin tests are among the most frequently conducted blood tests, as hemoglobin levels can provide vital insights into various health conditions. However, traditional tests are often underutilized... Read more

Immunology

view channel
Image: Under a microscope, DNA repair is visible as bright green spots (“foci”) in the blue-stained cell DNA. Orange highlights actively growing cancer cells (Photo courtesy of WEHI)

Simple Blood Test Could Detect Drug Resistance in Ovarian Cancer Patients

Every year, hundreds of thousands of women across the world are diagnosed with ovarian and breast cancer. PARP inhibitors (PARPi) therapy has been a major advancement in treating these cancers, particularly... Read more

Microbiology

view channel
Image: HNL Dimer can be a novel and potentially useful clinical tool in antibiotic stewardship in sepsis (Photo courtesy of Shutterstock)

Unique Blood Biomarker Shown to Effectively Monitor Sepsis Treatment

Sepsis remains a growing problem across the world, linked to high rates of mortality and morbidity. Timely and accurate diagnosis, along with effective supportive therapy, is essential in reducing sepsis-related... Read more
Copyright © 2000-2024 Globetech Media. All rights reserved.