Au Naturel is a LaTeX article template built on top of the standard article class, and which goes a decent stretch of the way towards looking like a paper in a Nature Publishing Group journal.
(For clarity, this is not an official class for any NPG journal, and any similarity is just gauged by eye. For Nature and its sister journals, the initial TeX submission does not need to be in any specific format; this template is only intended for aesthetic purposes.)
You can download the source here, or you can see and download the pdf file to see how it looks in more detail. For a starter, here is the first page:
(Note that the border has been added for better visibility.)
© Emilio Pisanty (2018), available under the MIT license.