IIT Guwahati is known for new research and innovations.
This time, the researchers of the institute have shown how some specialised protein molecules found on the cell membranes of all biological cells carry carbohydrate molecules into cells from outside.
According to a report, IIT Guwahati researchers have studied specific protein molecules called ABC transporters, present in bacterial cell membranes and they have shown that these transporters are selective about the type of carbohydrates they transport into cells.
The research team has been led by Dr Shankar Prasad Kanaujia, an Associate Professor of the Department of Biosciences and Bioengineering of the Indian Institute of Technology, Guwahati (IIT Guwahati).
The research work was published in The FEBS Journal and the paper has been authored by Dr. Shankar Prasad Kanaujia and students Monika Chandravanshi and Prerana Gogoi, who are doing Ph.D under him.
Any living cell needs glucose for life-sustaining energy and glucose in turn is obtained by the breakdown of carbohydrates like table sugar or sucrose, a simple carbohydrate, and starch, a complex carbohydrate, are some sources of glucose in the cell.
Such carbohydrates must be taken into the cell, and broken down inside the cell into glucose.
These carbohydrates are large molecules that cannot penetrate the membranes that surround the cell by themselves and depend on some special helpers or transporting molecules to carry them across.
The report quoted Dr Kanaujia as saying: “One of the largest classes of transporting molecules is the ATP-Binding Cassette (ABC) transporter, which is widespread in all forms of life.”
Table sugar and starch are only two of the numerous carbohydrates that are used by the cells, and they have to be preferentially taken into the cell.
While ABC transporters have been known for a long time, it remains unknown if these carbohydrate-ferries have preference for specific carbohydrates over others.
Many of the carbohydrates have similar structures and components, and differ in a specific type of bond or linkage, called glycosidic bonds. There are two types of glycosidic bonds – alpha and beta.
Dr Kanaujia further said: “We did not know if the ABC transporters have preference for any specific type of glycosidic bond.”
The research team studied the ABC Transport system of a bacterium called Thermus thermophilus that are present in hot springs, said the report.
In order to survive the extreme environment, the bacterium utilizes many kinds of carbohydrates for energy.
“Based on the preliminary analysis of the ABC transport systems of the bacteria we chose, we hypothesized that it would have different affinities for different carbohydrates,” the researcher further said.
In order to validate the hypothesis, the research team used X-ray crystallography techniques to determine the three-dimensional crystal structure of the ABC transport system connected to various types of carbohydrates having different kinds of glycosidic bonds.
“The specific ABC transporters we studied had increased affinity to the alpha-glycosidic bonds,” Dr Kanaujia said.
“The team also found an interesting phenomenon – the transporters had a higher affinity for simple glucose than complex carbohydrates, which meant that any glucose in the extracellular space would be preferentially taken into the cells over higher carbohydrates,” the lead researcher added.