Discovery of the First Archaeal Lipoprotein Biogenesis Enzymes Yirui Hong

Format:

Book

Thesis/Dissertation

Author/Creator:

Hong, Yirui, author.

Contributor:

University of Pennsylvania. Biology., degree granting institution.

Language:

English

Subjects (All):

0306.

0307.

0379.

0410.

0487.

Local Subjects:

0306.

0307.

0379.

0410.

0487.

Physical Description:

1 electronic resource (160 pages)

Contained In:

Dissertations Abstracts International 87-07B

Place of Publication:

Ann Arbor : ProQuest Dissertations and Theses, 2025

Language Note:

English

Summary:

Protein lipidation is a key mechanism for anchoring proteins to cell membranes. In bacteria, lipidation and membrane attachment of secreted proteins with a conserved lipobox motif ([L/V/I]−3 [A/S/T/V/I]−2 [G/A/S]−1 [C]+1) are mediated by prolipoprotein diacylglyceryl transferase (Lgt). Although archaea also encode lipobox-containing proteins, no Lgt homolog has been identified in archaea, suggesting the existence of distinct enzymes to accommodate the unique archaeal membrane lipids. In this dissertation, I identified and characterized the first archaeal lipoprotein biogenesis components (Ali). We surveyed lipoprotein presence for all major archaeal lineages and revealed a high prevalence of predicted lipoproteins across the domain. Comparative genomics using the distribution pattern of predicted lipoproteins identified a comprehensive set of Ali candidates, including two paralogs, AliA and AliB. Deletion of aliA and/or aliB in the model archaeon Haloferax volcanii impaired lipoprotein biogenesis and cell physiology, causing smaller colonies, slower growth, reduced motility, and altered cell shape, consistent with the broad functional roles predicted for the 93 Hfx. volcanii lipoproteins. Moreover, deletion of aliA completely abolished thioether-archaeol modification in lipoprotein extracts, revealing the chemical nature of archaeal lipoprotein anchors and confirming the essential role of AliA in archaeal protein lipidation. Conversely, aliB deletion had only minor effects, in line with the more severe physiological defects of ∆aliA compared to ∆aliB. Cross-complementation failed to restore the phenotypes to wild type, demonstrating functional divergence between the two paralogs. To further investigate their difference, I developed a large-scale TX-114 extraction coupled with mass spectrometry, which provided high proteome coverage and the first large-scale in vivo confirmation of predicted archaeal lipoproteins. Using this method, I showed that deletion of aliA significantly reduced the hydrophobicity of 60 out of 80 quantified lipoproteins. In contrast, only 36 lipoproteins were moderately affected in ∆aliB and largely remained hydrophobic, confirming AliA has a broader substrate range and stronger impact on lipidation than AliB. Collectively, these findings establish the critical yet partially distinct roles of AliA and AliB in archaeal lipoprotein lipidation, and open new avenues for lipoprotein studies in both archaea and bacteria

Notes:

Advisors: Pohlschröder, Mechthild Committee members: Daldal, Fevzi; Goulian, Mark; Maupin-Furlow, Julie; Lee-Gau Chong, Parkson

Source: Dissertations Abstracts International, Volume: 87-07, Section: B.

Ph.D. University of Pennsylvania 2025

Vendor supplied data

Local Notes:

School code: 0175

ISBN:

9798276001227

Access Restriction:

Restricted for use by site license