Postdoctoral Scholars

 
Sapanlika Swarnamali Baththana Madiyanselage, Ph.D. 

von Lintig lab

sxb1081@case.edu 


Sora Jin, Ph.D. 

Zhang lab

sxj572@case.edu


Meinan Lyu, Ph.D.

Yu lab

mxl1032@case.edu 

Research summary: 

Neisseria gonorrhoeae is a human-specific pathogen that causes the sexually transmitted infection gonorrhea. This pathogen has emerged as one of the most highly antibiotic-resistant Gram-negative bacteria. Multidrug efflux is a major mechanism that N. gonorrhoeae uses to counteract the action of multiple classes of antibiotics. The most predominant multidrug efflux pump is the MtrD membrane protein, which belongs to the hydrophobic and amphiphilic efflux resistance-nodulation-cell division (HAE-RND) family and confers resistance to a variety of structurally unrelated toxic compounds. We focus on solving the structures of MtrD and multidrug bound complexes by using cryo-EM, revealing how this membrane protein mediates resistance to various antibiotics. 


Chris E. Morgan, Ph.D. 

Yu lab 

cem137@case.edu 


Mitchell Moseng, Ph.D. 

Yu lab 

mam535@case.edu 


Wilnelly M. Hernandez-Sanchez headshot
Wilnelly Hernandez-Sanchez, Ph.D. 

Taylor lab

wmh31@case.edu

Research summary: 

Since DNA replication mechanisms are unable to extend the extreme ends of the lagging strand, a portion of genetic material is lost during each cell division. To compensate for this loss, the ends of all linear chromosomes contain repetitive DNA sequences called telomeres. A specialized enzyme called telomerase is responsible for the synthesis of telomere DNA and is essential for the retention of genomic material during continuous cellular division. Alterations to telomerase genes are associated with a range of diseases, including cancer, dyskeratosis congenita, aplastic anemia, and idiopathic pulmonary fibrosis. Whereas telomerase activity is undetectable in healthy adult somatic cells, it is upregulated in 90% of all metastatic tumor cells, allowing cancer cells to proliferate indefinitely by avoiding senescence. Because of the selective expression of telomerase in cancer cells, telomerase is a well-recognized cancer target.  Thus, cancer researchers must understand the fundamental and molecular processes related to telomerase enzymology in healthy and diseased states. Insights from the findings in this study could guide new mechanisms for the therapeutic regulation of telomerase function.


Vikas Hazarilal Sharma, Ph.D. 

Montano lab 

vhs11@case.edu


Kyle Whiddon, Ph.D.

Mears lab

kxw415@case.edu

 


Zhemin
Zhemin Zhang, Ph.D. 

Yu lab 

zxz964@case.edu

Research Summary: 

Acinetobacter baumannii is a Gram-negative, nonfermentative bacillus, which is considered as an important nosocomial pathogen causing pneumonia, urinary tract infections, bacteremia, septicemia, and meningitis. Infected by A. baumannii is extremely difficult to cure. One major mechanism that A. baumannii uses to mediate antibiotic resistance is the expression of multidrug efflux pumps, especially those belonging to the resistance-nodulation-cell division (RND) superfamily. The most clinically relevant RND-type multidrug efflux in A. baumannii is the AdeJ membrane protein, which extrudes multiple classes of antibiotics, such as tetracyclines, aminoglycosides, β-lactams, and fluoroquinolones. However, the substrate recognition mechanism of AdeJ is still unknown. Thus, an atomic level structure of A. baumannii AdeJ multidrug efflux pump bound with substrate complex will be the key point to reveal a mechanism on how AdeJ recognize and extrude the antibiotics. These data in the project will provide an essential structural foundation for future anti-bacterial drug discovery.