DNG are indeed readable in earlier versions of LR, but the trade-off is that one is generally limited to the so-called embedded import profile provided by Pentax. An up-to-date version of Lightroom will contain an Adobe Standard standard profile created by Adobe for your K-1 as well as several others that equate to several of your camera's custom image settings. It will also support PEF from the K-1. I don't know how things are for the K-1 (am not an owner), but for my K-3, I find the Adobe Standard is much more pleasing for initial import than the embedded.
The above being said, if one is using an older version of LR, say v5.6, up-to-date camera profile (.dcp) files including those for the K-1 are bundled with Adobe's DNG Converter software. The converter is Adobe's way of providing older versions of LR and ACR compatibility with newer cameras.*
Adobe Digital Negative Converter
BTW...the import profiles are more complex than one might assume. They are not ICC color profiles nor are they a set of presets. The author of the dcpTool profile editing tool has provided a short description...
DCP FIles
Steve
* I am running Lightroom v5.7 on Windows 7 and am able to import straight from the camera K-1 DNG files to Adobe Standard as well as "embedded" and five other profiles using the .dcp files stored as shared resources by the DNG Converter program. Doing an actual file conversion has not been needed. K-1 PEF support, however, requires conversion to DNG first.