Biology subjects

Cahill, M. A.

Publications and source records attributed to Cahill, M. A..

5 recordsLinked to original sources

bioRxiv2021

Structural characterization of a MAPR-related archaeal cytochrome b5M protein

We recently reported that the membrane associated progesterone receptor (MAPR) protein family (mammalian members: PGRMC1, PGRMC2, NEUFC and NENF) originated from a new class of prokaryotic cytochrome b5 (cytb5) domain proteins, called cytb5M (MAPR-like). Relative to classical cytb5 proteins, MAPR and ctyb5M proteins shared unique sequence elements and a distinct heme binding orientation at an approximately 90 rotation relative to classical cytb5, as demonstrated in the archetypal crystal structure of a cytb5M protein (PDB accession number 6NZX). Here, we present the second crystal structure of an archaeal cytb5M domain (Methanococcoides burtonii WP_011499504.1, PDB:6VZ6). It exhibits similar heme-binding to the 6NZX cytb5M, supporting the deduction that MAPR-like heme orientation was inherited from the prokaryotic ancestor of the original eukaryotic MAPR gene.

biochemistry↗

bioRxiv2021

MAPR origins reveal a new class of prokaryotic cytochrome b5 proteins and possible role in eukaryogenesis

The multiple functions of PGRMC1, the archetypal heme-binding eukaryotic MAPR family member, include steroidogenic regulation, membrane trafficking, and steroid responsiveness. The interrelationships between these functions are currently poorly understood. Previous work has shown that different MAPR subclasses were present early in eukaryotic evolution, and that tyrosine phosphorylated residues appeared in the eumetazoan ancestor, coincident with a gastrulation organizer. Here we show that MAPR proteins are related to a newly recognized class of prokaryotic cytochrome-b5 domain proteins. Our first solved structure of this new class exhibits shared MAPR-like folded architecture and heme-binding orientation. We also report that a protein subgroup from Candidate Phyla Radiation bacteria shares MAPR-like heme-interacting tyrosines. Our results support bacterial origins for both PGRMC1 and CYP51A, that catalyze the meiosis-associated 14-demethylation of the first sterol lanosterol from yeast to humans. We propose that eukaryotic acquisition of a membrane-trafficking function related to sterol metabolism was associated with the appearance of MAPR genes early in eukaryotic evolution.

evolutionary biology↗

bioRxiv2019

PGRMC1 phosphorylation status and cell plasticity 1: glucose metabolism, mitochondria, and mouse xenograft tumorigenesis

Progesterone Receptor Membrane Component 1 (PGRMC1) is expressed in many cancer cells, where it is associated with detrimental patient outcomes. It contains phosphorylated tyrosines which evolutionarily preceded deuterostome gastrulation and tissue differentiation mechanisms. Here, we demonstrate that manipulating PGRMC1 phosphorylation status in MIA PaCa-2 (MP) cells imposes broad pleiotropic effects. Relative to parental cells over-expressing hemagglutinin-tagged wild-type (WT) PGRMC1-HA, cells expressing a PGRMC1-HA-S57A/S181A double mutant (DM) exhibited reduced levels of proteins involved in energy metabolism and mitochondrial function, and altered glucose metabolism suggesting modulation of the Warburg effect. This was associated with increased PI3K/Akt activity, altered cell shape, actin cytoskeleton, motility, and mitochondrial properties. An S57A/Y180F/S181A triple mutant (TM) indicated the involvement of Y180 in PI3K/Akt activation. Mutation of Y180F strongly attenuated mouse xenograft tumor growth. An accompanying paper demonstrates altered metabolism, mutation incidence, and epigenetic status in these cells, indicating that PGRMC1 phosphorylation strongly influences cancer biology.

cancer biology↗

bioRxiv2019

PGRMC1 phosphorylation status and cell plasticity 2: genomic integrity and CpG methylation

Progesterone receptor membrane component 1 (PGRMC1) is often elevated in cancers, and exists in alternative states of phosphorylation. A motif centered on PGRMC1 Y180 was evolutionarily acquired concurrently with the embryological gastrulation organizer that orchestrates vertebrate tissue differentiation. Here, we show that mutagenic manipulation of PGRMC1 phosphorylation alters cell metabolism, genomic stability, and CpG methylation. Each of several mutants elicited distinct patterns of genomic CpG methylation. Mutation of S57A/Y180/S181A led to increased net hypermethylation, reminiscent of embryonic stem cells. Pathways enrichment analysis suggested modulation of processes related to animal cell differentiation status and tissue identity, as well as cell cycle control and ATM/ATR DNA damage repair regulation. We detected different genomic mutation rates in culture. A companion manuscript shows that these cell states dramatically affect protein abundances, cell and mitochondrial morphology, and glycolytic metabolism. We propose that PGRMC1 phosphorylation status modulates cellular plasticity mechanisms relevant to early embryological tissue differentiation.

cell biology↗

bioRxiv2019

Early eukaryotic origins and metazoan elaboration of MAPR family proteins

BackgroundThe membrane-associated progesterone receptor (MAPR) family consists of heme-binding proteins containing a cytochrome b5 (cytb5) domain characterized by the presence of a MAPR-specific interhelical insert region (MIHIR) between helices 3 and 4 of the canonical cytb5-domain fold. Animals possess three MAPR families (PGRMC-like, Neuferricin and Neudesin).\n\nResultsHere we show that all animal MAPR families were already present in the common ancestor of the Opisthokonta (comprising animals and fungi as well as related protistan taxa). All three MAPR genes acquired extensions C-terminal to the cytb5 domain, either before or with the evolution of animals. The archetypical MAPR protein, progesterone receptor membrane component 1 (PGRMC1), contains phosphorylated tyrosines Y139 and Y180. The combination of Y139/Y180 appeared in the common ancestor of Cnidaria and bilaterally symmetrical animals, along with an early embryological organizer and synapsed neurons, and is strongly conserved in all bilateral animals. A predicted protein interaction motif in the PGRMC1 MIHIR is potentially regulated by Y139 phosphorylation. A multilayered model of animal MAPR function acquisition includes some pre-metazoan functions (e.g., heme binding and cytochrome P450 interactions) and some acquired animal-specific functions that involve regulation of strongly conserved protein interaction motifs acquired by early-branching animals.\n\nConclusionsThis study provides a conceptual framework for future studies, against which PGRMC1s multiple functions can perhaps be stratified and functionally dissected. In accompanying papers we show that mutational perturbation of PGRMC1 phosphorylation status of the Y180 motif is associated with dramatic changes cell pasticity assayed by protein abundances, cell morphology, mitochondrial function, genomic stability, and epigenetic status, with pathways analysis associating Y180 mutation with processes related to organizer function. These combined works reveal previously unrecognized involvement of PGRMC1 in foundational animal processes of great relevance to disease.

evolutionary biology↗