Wednesday, 29 August 2018

Scientists Find Protein Role In TB Bacteria Growth

Indian researchers have identified the role of a protein which is critical for the growth of Mycobacterium tuberculosis (Mtb).

(Left to Right) Preeti Jain and Dr. Vinay K. Nadicoori

In their efforts to find new drug targets against tuberculosis, Indian researchers have identified the role of a protein which is critical for the growth of Mycobacterium tuberculosis (Mtb).

Researchers at the National Institute of Immunology (NII) in collaboration with CSIR- Institute of Genomics and Integrative Biology (IGIB) have determined the role of FtsQ, a critical cell division protein and shown that both increasing and decreasing amounts of this protein in Mycobacterium tuberculosis (Mtb) hampers its growth and division patterns.

This work builds upon research to understand the regulatory roles of set of enzymes known as protein kinases in Mycobacterium tuberculosis. “We were investigating the role of phosphorylation, a process which involves addition of phosphate group, of protein in controlling cell division. Interestingly, Cell division protein FtsQ was identified as one of the targets undergoing such regulatory modification,” said study leader Dr. Vinay Kumar Nandicoori.

The studies involved investigating various aspects of this pathogen related to its growth regulation, cell division and its survival in the hostile environment of the host cells. “While humans are the natural hosts of Mtb, for research purpose we use cell lines and mice models of infection,” he added.

Preeti Jain,  first author in this study, said, “We sought to understand how these pathogenic bacteria grow and divide from one cell into two daughter cells and how the process is controlled. While a lot is known about the proteins involved in cell division regulation in other bacteria, the identity of the majority of proteins in Mtb is still unknown.”

It was found that modifying optimum protein levels of FtsQ inside Mtb significantly influenced the average cell length, an outcome of abnormal cell division. While the initial decrease in the cellular concentration resulted in smaller cells, upon further decrease they became larger which eventually led to death.

"Cell length and growth regulation in Mycobacterium tuberculosis are currently an intense area of research. The findings are exceptional and exciting, making FtsQ an important target for new anti-TB interventions,” commented Anand Ranganathan, Associate Professor, Special Centre for Molecular Medicine, Jawaharlal Nehru University. He was not involved in this study.

The research team included Preeti Jain, Basanti Malakar, Mehak Zahoor Khan, Savita Lochab and Vinay Kumar Nandicoori (NII); Archana Singh (IGIB). The results of this study were published in ‘Journal of Biological Chemistry.’ This study was funded by the Department of Science and Technology.

Journal Reference:
Delineating FtsQ-mediated regulation of cell division in Mycobacterium tuberculosis

Thursday, 2 August 2018

Scientists Develop New Method to Synthesize Bio-Conjugates

Antibody-drug conjugates combine drugs with antibodies that specifically target tumour markers in cancer cells.

(Drs. Neetu Kalra, Vishal Rai, Sanjeev Shukla, M. Chilamari (Left to Right))

In a promising development in the area of targeted treatment of cancer, a team of researchers at the Indian Institute of Science Education and Research (IISER), Bhopal, have developed a new method to synthesize antibody-drug conjugates (ADC) using the chemical route.

Antibody-drug conjugates combine drugs with antibodies that specifically target tumor markers in cancer cells. When administered to patients, antibodies in conjugate track tumor markers and attach themselves to the surface of cancer cells. The antibody-market reaction triggers a signal in tumor cells which absorbs antibodies together with the drug.

However, the difficulty is that several amino acid residues in antibodies like lysine, tyrosine, tryptophan, cysteine, and histidine compete during installation of drugs. Amino acid residues also have multiple copies, each having a different level of reactivity making it difficult to identify the right one.

The researchers at IISER have now demonstrated that it was possible to synthesize an effective conjugate with lysine without much of a problem. The process makes use of 4-acetyl benzaldehyde, an electron-rich aromatic aldehyde, and triethyl phosphate, which is an organo-phosphorous compound used as a reagent.

“We had earlier demonstrated that it was possible to differentiate various copies of lysine for a level of reactivity and to selectively pick up the desired one, but we still could not develop a conjugate as we had used a metal-complex. Now the reaction is metal-free. A sequential formation of C-N bond and a C-P bond results in the labeling of lysine which is followed by installation of the drug,” explained Dr. Vishal Rai, leader of the team, while speaking to India Science Wire.

The team has developed conjugate of breast cancer drug, Trastuzumab, and anti-cancer drug Doxorubicin and tested its anti-proliferative effect on a HER2 over-expressing cancer cell line. After two days of treatment, the conjugate showed significant inhibition of SKBR3 breast cancer cell proliferation.

For evaluating selectivity of the conjugate, the researchers compared its anti-proliferative effect against a direct dose of Doxorubicin for effect on SKBR3 breast cancer cells and on the non-pathogenic HER2 negative MDA-MB-231 cells.

“The anti-proliferative activity towards breast cancer cells holds promise for further pre-clinical evaluation,” commented Dr. S. Chandrasekaran from Indian Institute of Science, Bangalore, who was not associated with this study. Dr.T. Govindaraju from Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, said, “specific advantage of this bio-conjugation technique is that it is metal-free.”

The technology is being transferred for commercial use through the IISER Bhopal based startup, Plabeltech. The research team included M. Chilamari, Neetu Kalra, and Sanjeev Shukla besides Dr. Vishal Rai.

The results of the study, funded by the Science and Engineering Research Board (SERB), have been published in journal Chemical Communications.

Journal Reference: 
Single-site labeling of lysine in proteins through a metal-free multicomponent approach