Forståelse av forholdet mellom struktur og funksjon til Vitellogenin i honningbia

This thesis focuses on the structure and molecular function of Vitellogenin (Vg) from honey bees (Apis mellifera). Vg is an ancient protein found in animals. Most biological processes depend on proteins' activities, and the structural shape of proteins determines what they can do and how they work. It is important to understand the shape and associated functional properties of honey bee Vg, as honey bees are important pollinators in our natural environment and agricultural food system. A yolk-protein that transports nutrients like lipids and zinc, Vg is necessary for honey bee reproduction, and the protein also regulates social behavior and has immune-related functions. Paper I presents a full-length protein structure for honey bee Vg, generated using computational structure prediction. For the first time, we describe the complete structural fold of the protein, revealing previously unknown structural features. In Paper II, I use structural- and sequence-data analysis to identify seven potential zinc-binding sites at different protein regions. Element analysis of purified Vg shows that, on average, three zinc-sites are occupied per molecule – a ratio not reported before. Paper III explores the Vg structure from the perspective of allelic variation on the honey bee vg-gene. We used amplicon Nanopore sequencing with barcoded primers to identify 121 Vg variants. With these data, I found that the domains and subdomains of Vg are characterized by different levels of variation. While some of these patterns were expected, my results also provide new insights on possible structure-function relationships. I use findings from Papers I, II, and III in Paper IV to develop a novel explanatory model for how Vg holds its lipid load. In sum, this thesis presents a detailed structural study that contributes toward understanding the multifunctional role of honey bee Vg.Denne avhandlingen fokuserer på strukturen og funksjonen til Vitellogenin (Vg) hos honningbier (Apis mellifera). Vg er et gammelt protein som finnes i mange dyr. De fleste biologiske prosesser er avhengige av proteiners aktivitet, og den strukturelle formen til et protein bestemmer hva det kan gjøre og hvordan det fungerer. De er viktig å forstå formen og de assosierte funksjonelle egenskapene til Vg i honningbia, ettersom honningbier er viktige pollinatorer i vårt naturlige miljø og for matproduksjon i landbruk. Vg er nødvendig for reproduksjon i honningbier som et egg-protein, ved å transportere næringsstoffer som lipider og sink, men proteinet regulerer også sosial adferd og har immunrelaterte funksjoner. Paper I presenterer en full-lengde proteinstruktur av Vg i honningbia, generert ved å bruke beregningsmessig protein-prediksjon. Vi beskriver en fullstendig strukturell form av proteinet for første gang, som avdekker nye strukturelle egenskaper. I Paper II, bruker jeg struktur- og sekvensdata-analyser til å identifisere syv potensielle sink-bindingsseter på ulike områder i proteinet. Element-analyse av renset Vg viser at tre sink-seter, i snitt, er bundet per molekyl – en ratio som ikke har blitt rapportert tidligere. Paper III utforsker Vg strukturen fra et genetisk variasjonsperspektiv i vg-genet til honningbia. Vi bruker amplikon Nanoporesekvensering med seriekodede primere for å identifisere 121 Vg-varianter. Med disse data fant jeg ut at domener og subdomer i Vg karakteriseres av variasjonsnivå. Noen av disse mønstrene var forventet, men mine resultater bidrar også til ny innsikt i forholdet mellom Vgs struktur og funksjon. Jeg bruker funnene fra Paper I, II, og III i Paper IV for å utlede en ny forklaringsmodell for hvordan Vg bærer sin lipidlast. Min avhandling representerer en detaljert strukturell studie som tar viktige steg mot å forstå den flerfunksjonelle rollen til Vg i honningbia.Norges forskningsråd ; BioCa

How Honey Bee Vitellogenin Holds Lipid Cargo: A Role for the C-Terminal

publishedVersio

Resolving the zinc binding capacity of honey bee vitellogenin and locating its putative binding sites

publishedVersio

Structure prediction of honey bee vitellogenin: a multi-domain protein important for insect immunity

Vitellogenin (Vg) has been implicated as a central protein in the immunity of egg-laying animals. Studies on a diverse set of species suggest that Vg supports health and longevity through binding to pathogens. Specific studies of honey bees (Apis mellifera) further indicate that the vitellogenin (vg) gene undergoes selection driven by local pathogen pressures. Determining the complete 3D structure of full-length Vg (flVg) protein will provide insights regarding the structure–function relationships underlying allelic variation. Honey bee Vg has been described in terms of function, and two subdomains have been structurally described, while information about the other domains is lacking. Here, we present a structure prediction, restrained by experimental data, of flVg from honey bees. To achieve this, we performed homology modeling and used AlphaFold before using a negative-stain electron microscopy map to restrict, orient, and validate our 3D model. Our approach identified a highly conserved Ca2+-ion-binding site in a von Willebrand factor domain that might be central to Vg function. Thereafter, we used rigid-body fitting to predict the relative position of high-resolution domains in a flVg model. This mapping represents the first experimentally validated full-length protein model of a Vg protein and is thus relevant for understanding Vg in numerous species. Our results are also specifically relevant to honey bee health, which is a topic of global concern due to rapidly declining pollinator numbers.publishedVersio

Identification of 121 variants of honey bee Vitellogenin protein sequences with structural differences at functional sites

publishedVersio

Understanding the structure-function relationship of honey bee Vitellogenin

This thesis focuses on the structure and molecular function of Vitellogenin (Vg) from honey bees (Apis mellifera). Vg is an ancient protein found in animals. Most biological processes depend on proteins' activities, and the structural shape of proteins determines what they can do and how they work. It is important to understand the shape and associated functional properties of honey bee Vg, as honey bees are important pollinators in our natural environment and agricultural food system. A yolk-protein that transports nutrients like lipids and zinc, Vg is necessary for honey bee reproduction, and the protein also regulates social behavior and has immune-related functions. Paper I presents a full-length protein structure for honey bee Vg, generated using computational structure prediction. For the first time, we describe the complete structural fold of the protein, revealing previously unknown structural features. In Paper II, I use structural- and sequence-data analysis to identify seven potential zinc-binding sites at different protein regions. Element analysis of purified Vg shows that, on average, three zinc-sites are occupied per molecule – a ratio not reported before. Paper III explores the Vg structure from the perspective of allelic variation on the honey bee vg-gene. We used amplicon Nanopore sequencing with barcoded primers to identify 121 Vg variants. With these data, I found that the domains and subdomains of Vg are characterized by different levels of variation. While some of these patterns were expected, my results also provide new insights on possible structure-function relationships. I use findings from Papers I, II, and III in Paper IV to develop a novel explanatory model for how Vg holds its lipid load. In sum, this thesis presents a detailed structural study that contributes toward understanding the multifunctional role of honey bee Vg

Structure prediction of honey bee vitellogenin: a multi-domain protein important for insect immunity

Vitellogenin (Vg) has been implicated as a central protein in the immunity of egg-laying animals. Studies on a diverse set of species suggest that Vg supports health and longevity through binding to pathogens. Specific studies of honey bees (Apis mellifera) further indicate that the vitellogenin (vg) gene undergoes selection driven by local pathogen pressures. Determining the complete 3D structure of full-length Vg (flVg) protein will provide insights regarding the structure–function relationships underlying allelic variation. Honey bee Vg has been described in terms of function, and two subdomains have been structurally described, while information about the other domains is lacking. Here, we present a structure prediction, restrained by experimental data, of flVg from honey bees. To achieve this, we performed homology modeling and used AlphaFold before using a negative-stain electron microscopy map to restrict, orient, and validate our 3D model. Our approach identified a highly conserved Ca2+-ion-binding site in a von Willebrand factor domain that might be central to Vg function. Thereafter, we used rigid-body fitting to predict the relative position of high-resolution domains in a flVg model. This mapping represents the first experimentally validated full-length protein model of a Vg protein and is thus relevant for understanding Vg in numerous species. Our results are also specifically relevant to honey bee health, which is a topic of global concern due to rapidly declining pollinator numbers