In HK97 capsid maturation, structural change (‘expansion’) is accompanied by formation of covalent crosslinks, connecting residue K169 in the ‘E‐loop’ of each subunit with N356 on another subunit. We show by complementation experiments with the K169Y mutant, which cannot crosslink, that crosslinking is an essential function. The precursor Prohead‐II passes through three expansion intermediate (EI) states en route to the end state, Head‐II. We investigated the effects of expansion and crosslinking on stability by differential scanning calorimetry of wild‐type and K169Y capsids. After expansion, the denaturation temperature (Tp) of K169Y capsids is slightly reduced, indicating that their thermal stability is not enhanced, but crosslinking effects a major stabilization (ΔTp, +11°C). EI‐II is the earliest capsid to form crosslinks. Cryo‐electron microscopy shows that for both wild‐type and K169Y EI‐II, most E‐loops are in the ‘up’ position, 30 Å from the nearest N356: thus, crosslinking in EI‐II represents capture of mobile E‐loops in ‘down’ positions. At pH 4, most K169Y capsids remain as EI‐II, whereas wild‐type capsids proceed to EI‐III, suggesting that crosslink formation drives maturation by a Brownian ratchet mechanism.
The EMBO Journal – Wiley
Published: Apr 6, 2005
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera