XML Feed for RxPG News   Add RxPG News Headlines to My Yahoo!   Javascript Syndication for RxPG News

Research Health World General
 
  Home
 
 Latest Research
 Cancer
 Psychiatry
 Genetics
 Surgery
 Aging
 Ophthalmology
 Gynaecology
 Neurosciences
 Pharmacology
 Cardiology
 Obstetrics
 Infectious Diseases
 Respiratory Medicine
 Pathology
 Endocrinology
 Immunology
 Nephrology
 Gastroenterology
 Biotechnology
 Radiology
 Dermatology
 Microbiology
 Haematology
 Dental
 ENT
 Environment
 Embryology
 Orthopedics
 Metabolism
 Anaethesia
 Paediatrics
 Public Health
 Urology
 Musculoskeletal
 Clinical Trials
 Physiology
 Biochemistry
 Cytology
 Traumatology
 Rheumatology
 
 Medical News
 Health
 Opinion
 Healthcare
 Professionals
 Launch
 Awards & Prizes
 
 Careers
 Medical
 Nursing
 Dental
 
 Special Topics
 Euthanasia
 Ethics
 Evolution
 Odd Medical News
 Feature
 
 World News
 Tsunami
 Epidemics
 Climate
 Business
 
 India
Search

Last Updated: Nov 18, 2006 - 12:32:53 PM

Howard Hughes Medical Institute

Cytology Channel
subscribe to Cytology newsletter

Latest Research : Cytology

   DISCUSS   |   EMAIL   |   PRINT
A riboswitch might sense magnesium levels in the cell
Apr 12, 2006 - 1:07:00 PM, Reviewed by: Dr. Priya Saxena

�Although there was no reason to think there should be any additional regulation, we found evidence that there was, indeed, an independent magnesium sensor in the cell,�

 
Magnesium, essential for energy-production and structural integrity, is critical to cell survival. Researchers have now found that cells use specialized segments of RNA called riboswitches to ensure that there is an adequate supply of the mineral. The newly described riboswitch can both sense magnesium levels and respond directly by regulating production of a magnesium transport protein.

Riboswitches are a recently discovered class of gene expression regulators. They control gene expression through a segment of messenger RNA (mRNA)�the copy of a gene that is used to produce a protein�that interacts with a target molecule to regulate its own translation into protein. Usually, the protein regulated by the riboswitch is part of the cellular machinery that regulates the levels of the target molecule.

In this case, the riboswitch lies on an mRNA that the cell uses to produce a transporter protein that carries magnesium into the cell. When the switch detects that magnesium has dropped to too low a level, it can boost the translation of the RNA�meaning the cell produces more of the transporter protein, thereby correcting the magnesium deficiency.

The discovery, which was described in an article published in the April 7, 2006, issue of the journal Cell, is important for two reasons, said Howard Hughes Medical Institute investigator Eduardo A. Groisman. First, the finding solves a biological puzzle about one of the cell's most important�albeit underappreciated�substances, he said.

Every energy-producing reaction in the cell depends on magnesium as an accompanying cofactor for the cell's main energy molecule, ATP. Magnesium is also essential for the stability of the cell's membranes and its protein-producing ribosomes. Nevertheless, almost nothing was known about how the cell senses low magnesium levels, said Groisman, who is at the Washington University School of Medicine.

The finding also helps advance understanding of how riboswitches regulate gene expression, which is quite different from the more familiar regulation by proteins called transcription factors. The proteins that transport magnesium into the cell�MgtA and MgtB�had been know for decades, Groisman said. And he and his colleagues discovered a decade ago that a regulatory system they called PhoP/PhoQ switches the genes for the transporters on or off in response to changing magnesium levels. �But before this work, it wasn't suspected at all that a riboswitch might sense magnesium levels in the cell,� Groisman said.

That mutation in the PhoQ protein should have rendered the cell unable to respond to low magnesium levels, but the transporter genes remained sensitive to fluctuations in the mineral, said Groisman.

So, the researchers decided to analyze in detail how the mRNA molecule for mgtA responded to magnesium, in hopes of discovering a basis for magnesium-sensing. To do so, they dissected the function of the components of the Salmonella bacterium's mRNA for mgtA by systematically altering those parts' function and observing the results.

Their studies revealed that a region at one end of the mRNA molecule�which is not translated into the MgtA protein�responded to levels of magnesium. A specific structure in this untranslated region, they showed, adopted different shapes depending on the level of magnesium in the bacterium.

In further studies, Groisman and his colleagues hope to understand in greater structural detail how the riboswitch senses magnesium levels�pinpointing the particular part of the molecule influenced by magnesium. Also, he said, the researchers will seek to understand how this magnesium sensor applies the brakes on translation of the mRNA into the magnesium transporter protein, MgtA.
 

- April 7, 2006, issue of the journal Cell
 

Abstract of the research article

 
Subscribe to Cytology Newsletter
E-mail Address:

 



Related Cytology News

How cells adhere so firmly to blood vessel walls
New Insight into Cell Division
New method for the controlled initiation of membrane fusion
CPK3 and CPK6 function as ion channel regulators in guard cell signaling
Disrupted Intercellular Communication Causes a Disfiguring Birth Defect
Sharing Responsibility for Clathrin Coat Assembly
Understanding the process of AIF release following MOMP during apoptosis
Researchers discover new cell structures
Cilia also contribute to cellular response to external signals
A riboswitch might sense magnesium levels in the cell


For any corrections of factual information, to contact the editors or to send any medical news or health news press releases, use feedback form

Top of Page

 

© Copyright 2004 onwards by RxPG Medical Solutions Private Limited
Contact Us