Navigation Links
How Montezuma gets his revenge
Date:6/14/2008

Every year, about 500 million people worldwide are infected with the parasite that causes dysentery, a global medical burden that among infectious diseases is second only to malaria. In a new study appearing in the June 15 issue of Genes and Development, Johns Hopkins researchers may have found a way to ease this burden by discovering a new enzyme that may help the dysentery-causing amoeba evade the immune system.

"This is the first enzyme to be identified that looks like it could mediate immune system evasion," says Sin Urban, Ph.D., an assistant professor of molecular biology and genetics at Hopkins.

The EhROM1 enzyme, it turns out, is part of an ancient group of enzymesthey are found in every branch of life from bacteria to manknown as rhomboid enzymes. In most animals, rhomboid enzymes seem to play a role in cell-to-cell communication, but a couple of years ago Urban found that malaria parasites use rhomboid enzymes for a more sinister purpose: to enter host cells uninvited.

That led his team to scour the DNA of other parasites to see if any of them also had genes that encode rhomboid enzymes. They found that the dysentery-causing amoeba Entamoeba histolytica contains one rhomboid enzyme and named it EhROM1.

"Plasmodia, the parasites that cause malaria, grab onto a host cell and push their way in," explains Urban. "Once inside they use rhomboid enzymes to cut themselves loose." But amoebas don't enter cells to cause dysentery, so Urban's team set out to figure out how these parasites use EhROM1.

They first identified protein targets cut by EhROM1 by looking for amoeba proteins that had structural signatures similar to those cut by malaria rhomboids. They found these signatures in a family of proteinslectinsthat are found on cell surfaces. The researchers put both proteins into cells and verified that EhROM1 does cut one particular lectin, and the more EhROM1 they added, the more lectin pieces resulted.

Every cell has on its surface proteins recognizable by sentries of the immune system that constantly survey the body for intruders, and amoebas are no different. To evade the immune system, amoebas shift all their surface proteins to the rear end of the cell then, like a dump truck, shed these proteins into the fluid around them.

Lectin, it turns out, is one of the proteins that during immune evasion moves to the rear and is shed by the amoeba. So collaborating researchers at Stanford University then looked to see if EhROM1 follows lectin and sure enough found that EhROM1 clusters at the capthe cluster of surface proteins waiting to be shed.

"We're excited to see if EhROM1 plays a specific role in the cap shedding during immune evasion," says Urban.

What's more, the EhROM1 enzyme is remarkably similar to those found in malaria parasites, suggesting that any potential drugs targeting EhROM1 might be able to treat two of the world's most prevalent diseases.


'/>"/>

Contact: Audrey Huang
audrey@jhmi.edu
410-614-5105
Johns Hopkins Medical Institutions
Source:Eurekalert

Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/26/2016)... ... June 26, 2016 , ... PawPaws brand pet ... product that was developed to enhance the health of felines. The formula is all-natural ... two main herbs in the PawPaws Cat Kidney Support Supplement Soft Chews ...
(Date:6/25/2016)... ... June 25, 2016 , ... ... and applications at AcademyHealth’s Annual Research Meeting June 26-28, 2016, at the Hynes ... important health care topics including advance care planning, healthcare costs and patient and ...
(Date:6/25/2016)... , ... June 25, 2016 , ... "With 30 hand-drawn ... specific project," said Christina Austin - CEO of Pixel Film Studios. , ProHand ... all within Final Cut Pro X . Simply select a ProHand generator and ...
(Date:6/25/2016)... ... June 25, 2016 , ... ... recover from injury. Recently, he has implemented orthobiologic procedures as a method for ... is one of the first doctors to perform the treatment. Orthobiologics are substances ...
(Date:6/24/2016)... ... June 24, 2016 , ... A recent article published June 14 ... The article goes on to state that individuals are now more comfortable seeking to ... operations such as calf and cheek reduction. The Los Angeles area medical group, Beverly ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... CLEMENTE, Calif. , June 24, 2016  American Respiratory Labs ... company, is now able to perform sophisticated lung assessments in patients, ... Technologies , Inc. Patients are no longer limited ... ndd,s EasyOne PRO ® , ARL patients like Jeanne R. of ... done in the comfort of her own home. ...
(Date:6/24/2016)... NAMUR , Belgium , ...  (NYSE MKT: VNRX), today announced the appointment of ... Board of Directors as a Non-Executive Director, effective ... the Company,s Audit, Compensation and Nominations and Governance ... Board, Dr. Futcher will provide independent expertise and ...
(Date:6/23/2016)... Any dentist who has made an implant supported ... Many of them do not even offer this as a ... laboratory costs involved. And those who ARE able to offer ... high cost that the majority of today,s patients would not ... Zadeh , founder of Dental Evolutions Inc. and inventor of ...
Breaking Medicine Technology: