Johannes AE4, Rome, 423-425 A.D. DN IOHANNES PF AVG, Bust right / SALVS REIPVBLICAE, Victory advancing left. RIC 1920 or 1923. Very Rare, nice example with clear name ending. Nathan www.RomanCoinAuctions.com
Johannes, eh? If you say so. I don't collect these mainly because it's next to impossible to find one in a condition where even I can identify it. I believe you when you say it's Johannes and now that you have ID'ed it as such, I probably could find it in one of my references. Otherwise, I would have no idea.
The key to attributing these is often the mint mark and field marks. However this one is even better since Johannes is the only one with a legend ending - ES PF AVG.