The Chelico lab at the University of Saskatchewan, Department of Biochemistry, Microbiology, and Immunology, is seeking a motivated researcher to study the biochemical mechanism of how APOBEC3 enzymes contribute to breast cancer.

Scientific Background: Cancers are caused by genomic instability at the level of the chromosome or nucleotide. Genomic instability originates from external carcinogens, inherited mutations, endogenous chemical damage of DNA, or as discovered in 2013, endogenous enzymatic activity of APOBEC3 (A3) single-stranded (ss)DNA cytosine deaminases.

The seven A3 enzymes in humans (A3A, A3B, A3C, A3D, A3F, A3G, A3H) deaminate ssDNA cytosines to uracils at specific sequence contexts and are normally expressed as an antiviral defense in germ cells, lymphocytes, and infected epithelial cells. A3 enzymes induce functional inactivation of viral DNA sequences through their promutagenic potential. A3 catalyzed uracils lead to C to T transition mutations in viral DNA due to uracil remaining in the template during replication. It is not known why but in some tissues A3 expression is upregulated (13-60 fold) and cytosine deamination happens in human genomic DNA when it is transiently ssDNA, such as during replication or repair. Depending on the cellular context, the uracil can escape faithful repair and be a template during DNA replication or promote transversion mutations if the uracil is excised and repaired via low fidelity DNA repair pathways. Multiple cancer genomes contain mutations in sequence contexts that match the in vitro deamination specificities of A3A, A3B, and A3H haplotype I.

Primary Purpose: While there are genomic and clinical studies correlating A3-induced mutations with cancer, many of the mechanistic steps in how the A3 activity that induces uracils results in the broad type mutations in cancer genomes and how their protein interaction network affects their activity remain to be determined. The successful candidate will carry out work and train others in methods to purify proteins and conduct in vitro assays with proteins and DNA substrates or protein interactors to determine mechanisms of A3-induced somatic mutagenesis

Typical Duties and Accountabilities: The candidate will:

Conduct experiments independently and troubleshoot technical issues Learn new techniques and stay current with relevant literature Help train new lab members Order supplies and manage inventory Assist with lab organization and coordination with the PI Demonstrate strong multitasking and time management abilities

Education and Experience: The successful candidate will have an M.Sc. or Ph.D. in the biomedical fields of Biochemistry, Microbiology, or Immunology and at least 2 years of hands-on laboratory experience.

Skills:

Experience with protein purification using bacteria and/or insect cells Familiarity with purification of native and/or tagged proteins Proficiency with FPLC systems for gel filtration and ion exchange column chromatography Use of purified proteins for in vitro assays, particularly for protein-DNA interactions and kinetic analyses Gene cloning and site directed mutagenesis

Experience working in a collaborative lab environment and participating in manuscript preparation is considered an asset.

How to Apply: Applicants should submit their C.V. along with a one-page cover letter titled “I want to work on APOBECs and cancer”. The cover letter should detail:

The experience(s) you have applying the skills described in the candidate description and how they make you suitable for the position An example of how you have experienced and dealt with competing priorities and multitasking A summary of a project idea based on what interests you in these recent lab publications: PMID: 38548018, PMID: 37324648, PMID: 36444883

Applications will be accepted until a suitable candidate is found. Appointment type will be commensurate with education and experience.