Senior Scientist/Principal Scientist, Expression

About Xaira Therapeutics

Xaira is an innovative biotech startup focused on leveraging AI to transform drug discovery and development. The company is leading the development of generative AI models to design protein and antibody therapeutics, enabling the creation of medicines against historically hard-to-drug molecular targets. It is also developing foundation models for biology and disease to enable better target elucidation and patient stratification. Collectively, these technologies aim to continually enable the identification of novel therapies and to improve success in drug development. Xaira is headquartered in the San Francisco Bay Area, Seattle, and London.

About the Role
We are seeking a Senior or Principal Scientist to join our team and lead from the bench. The ideal candidate will have a strong foundation in protein expression in both eukaryotic, prokaryotic and cell free systems, with demonstrated expertise in cloning techniques essential for therapeutic protein development.  Candidates with pharmaceutical or industrial experience in protein production at scales ranging from microgram to gram scales are strongly preferred.

About You
The successful candidate will have a strong understanding of the biophysics of protein-protein interactions, protein chemistry and extensive experience in the molecular biology and biophysical techniques essential for protein engineering. You will be expected to work independently, drive scientific execution in the lab, and provide technical leadership on complex projects.  Supervisory or mentorship experience is desirable, as is the ability to collaborate effectively within cross-functional teams spanning discovery, process development, and analytical functions. Strong communication skills and the ability to present scientific data to diverse audiences are essential.  We are looking for a highly adaptable individual who can excel in a fast-paced, matrixed environment with shifting priorities and multiple responsibilities. This is a hands-on role suited for a scientist who is passionate about advancing drug discovery and development through innovation and scientific rigor.

Key Responsibilities

• Protein expression in multiple systems including mammalian, prokaryotic, insect and cell free systems is the primary responsibility.
• Downstream processing of samples including harvesting cells in small scale and up to 20 L using depth filters, affinity chromatography, ion exchange chromatography, and sizing.
• Use of various analytical techniques to evaluate process efficiency and quality.
• It is anticipated that this will require creative and unique approaches, including construct design and screening to increase yields, the development of novel strategies and methods for difficult to express proteins and to increase stability of problematic proteins.  The target proteins will be therapeutic proteins, antigens for the generation of therapeutics, assay reagents for screens, and proteins for structural studies.
• Experience in high throughput expression and purification is expected.
• The experience and flexibility to work on downstream purification is required.
• Leadership and mentoring of team members is expected.
• Excellent record keeping and organization is a must.

Qualifications

• PhD with 8+ years of industry experience is required.
• Strong technical background in protein expression, tissue culture, aseptic techniques, and the operation and maintenance of bioreactors in an industry setting a must.
• Experienced molecular biologist with the ability to design and make expression constructs is required.
• Mammalian transient protein expression and cell line generation is required.
• Experience with insect cell expression using baculovirus and S2 cell line generation is strongly preferred.
• Experience with prokaryotic and cell free expression is a plus.
• Hands-on experience in generating and managing research cell banks is essential.
• Experience in protein purification and protein characterization is required.
• Experience with HPLC and FPLC techniques is desirable, specifically, knowledge of Agilent HPLC and Cytiva AKTA systems. 
• Downstream medium scale (10 - 20 L) sample preparation for purification.
• Protein analysis for expression including SDS-PAGE, CE-SDS, glycosylation analysis, cIEF and BLI/SPR.
• Demonstrated expertise in protein expression processes, ranging from 96-well plate formats to scales of up to 10-liter bioreactors, is required.
• Proven expertise in biological research, demonstrated by publications in peer-reviewed journals, issued patents, and successful IND filings.
• Track record of independently leading complex research projec